...Yes, and no...I can think of another 5 years worth of books for ArM5x without even trying hard. 
...and thinking of it, if you go ArM6, it has to keep the magic system. That's my only caveat. Do what you must with the rest, but keep that beautiful engine.
-Ben.
Intentionally so I believe, to underscore how combat is not the main focus of the game.
Unlike eg. That Other Game.
Contested Isle, p. 102 (under header of Baí Brasse), or apparently LoM p. 120.
Ah, like in the old days then?
When the sale was theoretically 1-10, but I don't recall seeing virtues above +7 (Immortal, 3rd ed) or flaws below -8 (Leprosy).
Are any of these in need of an extra player, not situated in the UK?
No? Drat!
You could flip this around, We already have an excellent catalog in fifth why dump it with insufficient backwards compatibility instead of leveraging it to sell the new game?
New and different needs justification at least as much so if not more than an improvement of what we have. Cleaned up rules with hundreds of tiny-moderately significant tweaks plus a more inclusive and better organized core book seems to me to be an excellent justification.
How many fourth edition games are out there that aren't based on "we can download the rules for fourth ed. for free"?
I know of three but all began before most of Ars 5th came out or it was free. Anna and Q don't post on here nor Guy actually so we don't hear from those who stayed with 4th, but we do have Spidermage who runs a twenty year old Ars 3 game?
That's not really a good excuse to not improve those rules, though.
What I would like to see in AM6 is more consistency between books. I don't want to look at a price list in covenants and a productivity chart and income in City & Guild and sit there going "But how do they make more money than stuff?" I want rules for equipment bonuses to not depend on which book I am pulling them from. I don't want RAW that was generally considered established to shift because someone decided to put their house rules into a now published book.
Hmm... This is the... 4th or 5th thread that has come up here? Here's some historical threads:
viewtopic.php?f=4&t=29731&hilit=6th+edition
viewtopic.php?f=4&t=9731&hilit=6th+edition
viewtopic.php?f=4&t=19604&p=170052&hilit=6th+edition#p170052
viewtopic.php?f=4&t=9384&p=144410&hilit=6th+edition#p144410
viewtopic.php?f=4&t=7323&p=107141&hilit=6th+edition#p107141
viewtopic.php?f=4&t=6420&hilit=6th+edition
I think first off, what I would want in a 6E, is that the Order of Hermes be dramatically integrated far better into Mythic Europe. The biggest bugaboo of all I have with Ars, low power, or high power, is WHY HASN'T HISTORY BEEN CHANGED?! In order to do this would require a mature look at a game that was developed by a bunch of college students in the late 80s who had poor world design ideas and all sorts of issues endemic to RPG design of the time.
Names like Jerbiton - seriously, where did this come from - someone's acid trip?
I think a move to the early days of the Order, late 700s or early 800s would be a great one.
If we're just going to clean up the rules, centralize them in the core book and not change the history or setting, then sure, lets do a 5.5.
Everyone has SOME issue with Ars Magica depending on play and GM style. However, the game works reasonably well. You want borked game design? Look no further than Scion or Exalted.
Perhaps you folks might start by answering this important question (something that I've asked in many previous development cycles):
What makes a game Ars Magica?
In other words, what are the game's essential qualities? Are they mechanical, thematic, procedural, aesthetic, or a mix? When does it stop being Ars Magica for you? How much would it not resemble ArM5 while remaining Ars Magica?
And a followup:
Who is ArM 6's audience?
For the former, I'll say something that is being hinted at in the other thread: there is no Essential Nature of Ars Magica, there are only components, and whether Ars Magica remains Ars Magica after a change will be hotly debated by True Fans(tm) until the Last Judgment.
For the latter...I think there's a niche for spreadsheet nerds who happen to enjoy narrativist RP, or alternatively, narrativist/history buff types who don't mind spreadsheets, and in either case it's for people who trust their SG and don't mind not having a tight system. To the extent that ArM isn't as broken as Exalted, it's because ArM deliberately de-emphasizes combat from its narrative and has a strong enough social structure that even magi can't solve a social combat (among magi) just by drawing a sword, because Wizard's War is a carefully-restricted pain in the rear to keep every encounter between magi who don't like each other from ending in a blast-out.
https://forum.atlas-games.com/t/what-makes-ars-magica-ars-magica/9249/1
We are ahead Cam I asked that yesterday! 
probably makes more sense for people to reply in that thread.
If you don't allow the RAW to shift (and this edition generally doesn't) then what you get are godawful kludges like in Magic where magical beings have things which are exactly like virtues and flaws, and can be traded 1:1 for virtues and flaws, but are not virtues and flaws because the rule saying characters can only have 10 virtues is unbreakable.
What I'd like is Edition 6 to have an electronic edition as its core document and the paper edition to be nice, but just a thing. That means when get errata, they are not just on the Ars Magica fanpage, they get loaded into the core document. It also means if we get to a piece where, say TL has said "There are only five covenants in Transylvania" or Normandy has said "There is no covenant in Constantinople" we can say "Um, OK...we didn't realise we were actually piling up trouble here. We take that back." (btw: both of those problem sentences there are mine.)
...and if you hate it, then you just use the version of 6 that was live when your saga started.
So, I don't want the new rules to be shackled to the old ones. I'd prefer the reverse: I'd like the core rules to be a living document so that if, for example, I come up with a brilliantly better way of doing longevity potions, as I believe I have, it doesn't need to hand around until the next edition to go into the Core. If someone writes a great article for SR, and the line editor thinks its great? That can be uplifited into the Core.
So, for me, that's my Big Wish. I don't want a paper book plus an eventual PDF. I want a subscription service where I get sent electronic Ars, with patches. I'd buy the books just because I like books...but, I'd like the Sixth Edition to be a Perpetual Electronic Edition.
Well, first edition did have a Latin inscription in it suggesting that enlightenment could be found in burning herbs...
I'm not sure if my folksonomy for this made it into the new edition, but, yes, there's a really basic problem with someone who speaks Lating having a J in his name. "Ierbitonus" makes no damn sense at all as a name.
I also think we should ditch Tremere and the Order of Hermes, in case Atlas ever wants to sell shirts. Just because they have a really forgiving license doesn't mean they shouldn't develop their own IP's brands.
Apart from the Major/Minor virtue split (which I initially didn't like as well, but now appreciate) I basically agree with everything in this post.
Also, tie the systems from the supplements into the corebook as far as possible (that is people without the supplements still need to be able to use the presented material).
Edit: Speaking of which...
Another thing I would like, but am probably in the minority here, is a more complex aura system so we don't wind up with historical kludges about what group is magic or faerie when it comes to the fallen gods (actually I'm thinking fallen gods could make a nice supplement). I'd like to see auras for primal, Vedic, Geni, faerie, a combined aura of infernal and divine (on the basis that it represents a single religious perspective, two sides of the same coin), and magic, but that is also due to the fact that I get frustrated that only monotheistic faith can generate an aura, which despite how some people read it, seems to me to be taking a very strong religious stance within the game world to the point of defining an objective truth that somehow not everyone sees. I also think combining the divine and infernal aura makes things like the crusades much more explainable and ambiguous where morality might lie for those within the faith.
Timothy, please don't take this personally, but I hope you never end up becoming line developer of a potential sixth edition. I couldn't imagine a person's ideas for a given game being farther away from mine than is the case with you. And in this case I basically speak for my whole table of players. 
My understanding always was this rule only applied during character creation. Otherwise initiations broke this rule right at the start of the edition.
D&D Next is attempting this and I'm predicting it will fail. The high-maintenance digital edition will only be accepted by a part of your target audience (there's still a sizeable lot of "conservative" players who value the paper in their pen & paper roleplaying experience) and constantly changing the rulesets will cause further fractioning of your existing customer base. D&D4 already suffered from this, D&D Next will probably break upon it. Pathfinder succeeded with its monolithic model, building their publishing model around their bestselling corebook.
Ars Magica 5th Edition was a huge success as in that it found uniform acceptance by pretty much the entire spectrum of established Ars Magica players. There was never any edition war and it was generally accepted as the best edition there ever was for the game. This puts the entrance barrier for a 6th Edition extremely high as Atlas Games will have a problem improving upon something that already hit the general consensus of its audience square in the jaw. It seems they already found the smallest common denominator and any change from that is bound to lose them sales.
I do realize the problem in this as from a business standpoint, corebooks sell the most. There needs to be a new edition of Ars Magica sometime in the future to "reboot" sales figures and for the line to remain viable. But my personal opinion is that a revised 5th edition would end up generating more total sales down the line than an "experimental" 6th edition.
Oh, yes. I'd like a new combat system. Now, my personal take is that I'd like it to be based on narrative control but mostly because I played in a game of Lot5R yesterday and you can see that it and Ars share some genetics, but my GM kept telling me the results of rolls, and I hated that.
I've had a couple of shots at designing a noun-verb combat system based on the Arts. I thought that if we could not get the Art scores to work on the Ability scale we might go the other way. So your verbs would be
Attack
Defend
Switch
and your nouns would be
Single Weapon
Long Weapon
Great Weapon
Bow
Brawl
No worries. Toa. 8) Let me ask you though: do you like having to pay for the rules on how faeries work over and over and over again? Do you like every book with demons in it needing a page to tell you they can't plan? No matter how good 6 is, when we grapple with it as authors, we are going to find new levels of coolness. I'd like a way of incorporating those without having to wait for the edition to roll over, like Mystery initiations needed to.
It's still a place where a distinction without difference is used to sidestep an earlier sentence. See also Transylvania. I think we did some good work there because of the creative restriction, but it's another example where we have said "The rules say you can't eat chocolate, so we are just going to call this thing here that looks, tastes and smells like chocolate "Etalocohc" and hope for the best."
I doubt that. Then again, I spend a lot of time working with ebooks so I may be ahead of the curve here.
Five years ago, yes. In 2009. Things have moved on a lot. Games with a bajilion little modifiers like Ars benefit tremendously from electronic integration.
This assumes the current audience is the only audience, though. That's definitively death. That's exactly how games die, then hide out for a decade and come back as a kickstarter license.
If you really want no big change, then the future for Ars is pretty much the same as the future for Pendragon. Atlas gets to the point where it is so far from their card game business that they spin it off to the equivalent of ArtHaus and it becomes an interesting curio, updated when Greg Stafford or the perpetually-aging fanbase have the time. Ars, and I know people will hate me saying this because gamers always do, only survives in the long term if it gets new people in, even if it needs to sacrifice some of us who are already in the tent to do it. That's just how it is. I know that annoys people. The sad-but-true thing though is that Ars can't just keep its current fans happy.
A new label on the front of 5 doesn't do this, though.
From my perspective as an author, the point of the reboot is to get more authors in. You need to get to a point where you can say to an author "You may write for us without having to read the earlier books". and that means every so often you need to burn the canon down to the foundations and let people start from scratch. And yes, I know that means my stuff gets burned to the ground. That's inevitable and necessary, unless we somehow get to the point where Ars author make a living from being Ars authors.
As someone with a 'respectable' library of PDF RPG titles (over 100), my opinion is this:
PDFs are great tools for reference (especially if they've been bookmarked properly). They are terrible tools for use in play.
Part of this has to do with the terrible, terrible coding of PDF files in general. I keep hoping for the day when something better crops up and becomes the new standard. Something's wrong when I can flip through web pages faster than through a file stored on my PC (which isn't some ancient box of suck) or Galaxy Note 3.
The other half has to do with portability and scale. Books are far easier to read and handle than tablets due to size and durability (dropping a book results in bent corners, dropping a tablet can destroy it - so you handle tablets far differently). Further, if I have to use multiple books, moving between the two is largely seamless, but I'd need a very large monitor to do the same with PDFs.
I primarily use PDFs for 2 reasons: First, to test a system out (evaluate it before I spend money on a physical copy), and second, to have a portable reference of peripheral material for when I'm a player (as a GM I want physical books to use, far superior).
So for Ars6, books all the way. Living PDFs are great for getting errata fixed, and print-on-demand looks like a very viable option for the RPG industry's future.
Aaaand,
Here we go again!
Re "what makes AM AM" I think I've said mine in a previous thread.
I loosely outlined more complex auras in another, but not a specific system.
As for books vs pdfs vs evolving electronic editions... I love physical books. I buy these. I don't buy gaming pdfs. I love Pathfinder's searchable database. D&D4 had continually changing rules via digital errata, which made the books pretty useless pretty quickly; to stay up to date one needed a subscription. This did not destroy the market for the game iirc, even though the WotC website was painful to use, at least during the free evaluation period when the game came out. A subscription with a good app and search engine is plausible, though I would still miss physical books. (Cue BtVS quote from Giles about knowledge being smelly.) Artwork would mostly get in the way here, since moving more bits around --> wasting more compute/download/render/retrieve/etc time and valuable screen real estate.
As an aside about artwork, some months ago I finally bought the new edition of Nobilis along with the last few AM books, and padded my order with some other gaming books I had heard about. To my surprise, the book I have spent the most time with was the one I expected to be the least interesting: Anima. The artwork probably swayed me to some degree , and I am apparently not immune to such things. The art works well for my physical copy; I have since seen pdfs that load painfully slow. I enjoy that artwork too, yet would prefer it gone. And using the pdf as a reference isn't much fun, since pdfs are really not optimized for the screen (since they reproduce book pages, which are not the same thing at all, even if a screen is large enough to display a page with high quality.)
One thing that I think D&D4 got right, at least to some degree, is that NPCs and PCs are different, and can still work even if they are developed using different rules. In AM, I think something is lost when all creatures are developed according to a single set of rules: Weird powers become difficult because there is a fixed set of rules that have been (vaguely) balanced to work with PCs. For example, I had always assumed that when the canonical Magic Wolf becomes a pack, none of the wolves need to penetrate with their attacks. But that's not so, because of the general rules for MR. A creature's deadly poison is built as a power, so it has to penetrate (but a cobra's does not). The weirder powers are impossible to build. Rules for NPCs of this kind get in the way; maybe a different kind of rules set would serve better. The game is about wizards, and wizards are different from other people, so who needs the same rules if the game works better?
Age and wizards: The ancient wizard is a trope, but so is the wizard or witch who enjoys unnatural extended youth (usually due to some ancestor or nasty undertaking). I think it would be cool to have a wizard's appearance reflect who he is and be utterly unrelated to actual age. You're a studious Bonisagus or a wise and trusted Guernicus mediator? You start to look older and wiser faster. You're a flirtatious Merinita or Jerbiton troubador? Young. And so on. Extended shifts of personality or activity can change appearance, and maybe Twilight Scars involve both changes in appearance and required evolution in personality that cannot be undone (decided by the player, of course), representing the development of Essential Nature (an idea that is associated with the Magic Realm) that begins to subsume the essential choice and malleability of humanity.
Got to go for now.
Anyway,
Ken
TOA, I'd agree with you on the craft magic thing, except I'd take out and make it a house mystery of house Verditius. Pretty high end one...