I have a few questions for what the future will hold for Ars Magica:
Well, after Hibernia, there'll only be one tribunal that hasn't received a Tribunal Book: Provence. I can't say for sure, but I suspect updating older tribunal books isn't a terribly high priority.
The only other book that's been officially announced is an Egypt/North Africa book slated for sometime in the next few years.
Sadly, Steve Jackson Games has put its plans to offer PoD services through E23 on hiatus for the time being. 
I am too, and i would like to take the opportunity to congratulate the whole 5th edition creative team past and present on what is currently the finest RPG in production. I first came to the game about three years ago when I downloaded the rules simply because I was curious about the game. I had a vague recollection of it being released in the 1980's and had no great expectations.
I was personally shocked at the depth of the game, its various subtle touches and the production qualities. I couldn't believe that such a gem was out there all that time and I had never had the enjoyment of playing it. It just leaves D&D, pathfinder and all the other stuff out there looking like dross. I just had to buy everything and did so. What is also interesting is how much better the 5th ed is over the 4th ed and what I would really like to get across to the whole creative team is to urge them to keep on doing what they have been doing. They don't need to change anything. The books are great, great, great value for money, look beautiful and the detail is the envy of all the other so called "publishers".
Atlas has had to date a clear commitment to great products. Just look at how good the 3rd ed OGL stuff is compared to the other crap produced at the same-time. If you haven't looked at En-Route, do so soon. I would like Atlas to keep on producing great products by sticking with its proven formula for quality. I make no apologies for the sycophantic tone of this post but its something I have wanted to say to the Atlas crew for awhile and it deserves to be said.
I doubt Atlas will answer officially, but hope spring eternal...
As others said Provencal seems the only one missing, and they're doing one per year so it would probably be released in 2014. It then isn't clear whether they'll continue re-making the ones that were already done in prior editions, but my guess is that they will - at the same pace. And the one the fans voted as the most-in-need-of-revision was Rome. I'm guessing Atlas agrees. So my guess is: 2014 Provencal, 2015 Rome, 2016 who-knows.
You might want to check out this thread.
Unfortunately, Atlas keeps future products secret for fairly long...
I thought so too, but now I believe the policy has changed to "we do rgw PDF-thingie we have the time to; probably before the first printing is gone". This thread suggests that still "... but not before a new book is released" is another criterion, and that you should blame Cam Banks for any delays 
I, for one, am waiting eagerly for Tales of Power to reach PDF... I'd settle for Antagonists for now... really..
I, too, am a dedicated fun of Fifth Edition because of its superb writing and production quality. The more I read the core book, the more I appreciate what a work of art it is. And the supplements are consistently good, for years now. This is an amazing achievement for Atlas, made possible by great writers. So I'm just taking this opportunity to say - thanks.
First, thank you, everyone, for the sycophancy. I really appreciate it, and I imagine the authors do, too.
I'm particularly grateful for it because it provides a neat segue into explaining why I'm not going to answer the first two questions in any detail.
Ars Magica is a small, niche game. That means that the authors are all essentially volunteers who get a little something to say thank you for their efforts. However, they are very professional volunteers, in the sense that they do what they are supposed to do, follow instructions, and put in a lot of work to maintain the quality of the line. Nevertheless, good RPG material is hard to write, and good Ars Magica material harder than many other games. There is another vital step in the process: playtesting.
We send every draft out to playtest at least twice, and at least three groups look at it every time. They spend a couple of months using and reading the draft, and send us lots of comments. These comments really are an essential part of the process, and the playtesters are pure volunteers, who just get a couple of copies of the book (between each group) as thanks. Don't miss the playtesters out of your thanks. We revise the draft based on the comments, and then send it back out for playtest. Ideally, the second draft comes back with only minor comments ("this spell has its level miscalculated", for example), and we can polish it and publish.
However, that is not always what happens. In order to maintain quality, we have to be ready to throw away whole drafts and start again if the approach taken first time around was fundamentally flawed. We have done that. We have done that more than once. In general, the authors are willing to do it. But it takes time. The authors all have day jobs that pay the bills. (Well, nearly all, and the ones who don't live in poverty, which creates problems of its own.) If a major revision is needed, that generally pushes the book back by six months. First, it will take a few months for the author to write another first draft. Second, that draft is very likely to need two rounds of playtest, because it is fundamentally different from the first draft.
This means that things get delayed. Apprentices was delayed long enough for my daughter to be conceived, born, and start kindergarten between the planned and final release date. If we announced things early, we'd have a terrible reputation for delays. So, we don't announce things until the draft is done, edited, turned over to Atlas, and has gone into the final proofing and layout stage. This means that any delay you know about really is Cam's fault; the delays that are my fault are kept secret. (This is an excellent strategy, if I say so myself.)
So, I'm not going to say anything specific about what is coming in the future. The obvious books are likely to happen, but we also try to do books that weren't obvious in advance.
As for PDF/POD, that's not my department, so I can't comment, because I don't know what current thinking is. Being thousands of miles away from the Atlas offices does have a few disadvantages, and one is that I don't get to hear casual discussions.
It's my department, so I'll comment.
PDF: Our current practice is that the most recent four releases are in print only. Since we aim to release about four books a year, that means it's about a year after release in print that we start selling a PDF of each book. Depending on what else distracts us on the 'to do' list, it's usually within a month or so of each new print release that we make the four-books-ago book available as PDF. Hence, after Tales of Power (stock # AG0304) was released, we made the Apprentices (Stock # AG0300) PDF available for sale.
Print on Demand: This tends to have two meanings in the trade. One is a service that literally prints a single copy of a book and mails it to a customer in response to the order, using digital printing. The second is the kind of digital printing that is used, and is relatively economical on what are (by traditional print standards) extremely small print runs (sometimes just a single copy).
We have made use of the latter, in order to keep softcover versions of certain 5th edition sourcebooks available in the market through our usual channels. Examples are the softcover reprints of Realms of Power: Divine and Houses of Hermes: Societates. The unit cost for those softcovers is actually higher than the original hardcovers; however, we print only 50 to 150 copies, so we tie up a lot less money in the inventory (and the original print runs recouped fixed development expenses), and when our stock runs out we can replenish it in under two weeks. I don't expect that all 5th edition titles will be kept in print indefinitely, but for important books like the Houses of Hermes and Realms of Power series, this allows us to keep them available in a way that makes economic sense.
I must admit I truely appriciate this strategy. These days, when I aquire new RPG-products, they are usually either Ars Magica, or from a certain other company, who shall remain nameless in this context. This other company used to announce their planned products well in advance - I've seen them provide a pdf with what was planned for the next 2 years.
Unfortunatly, that's a bad strategy. Most of those books had delays on the order of half a year - this came to be the expected standard.. One was mentioned as a sourcebook, but came out 2-3 years later as what was essentially a new core book.
In recent years, they have cleaned this up a bit, but only by not announcing so far in advance.
On top of this, the rules are... mush less tested than in Ars Magica. There are entire chapters apparently written by people who may know the rules, but certainly do not understand them.
The core books have a list of playtesters, who may or may not have done their work, but it does appear that where their feed back clashed with the authors' ideas, the testers appear to have been ignored (or the original draft was truely sad). The supplements have no playtesters listed. I'm not surprised.
One cynical lad of my aquintance suggested that they thought they were publishing software and had heard the saying "Release Early - Release Often." But this strategy doesn't work nearly as well with printed books.
Compared to this, I certainly prefer the approach taken by Atlas Games.
Let me guess... White Wolf/Exalted?
I think the strategy of announcing books 6 months in advance when it's actually ready to go is fairly brilliant.
And yes, I think Whitewolf /Exalted is definitely the one being mentioned here. Love the game but man did they fuck it up. Onyx Path publishing (who now does the work) have cleaned this up a bit, but still, providing the release dates when they weren't able to hit anything on time was a big screw up. From what I've gathered for Exalted 3rd Edition, they're holding to a much longer production schedule and saying things will take a while, and do much fewer books per year,but quality books instead of # of books.
Of course, who's even worse than WW is Palladium Games with Kevin Sembia.
So, speaking of the future, I'm curious what kind of supplements will come out, many of the "obvious" ones have been done, and so now I'm genuinely curious what the "not obvious" books are. I've been reading and playing this game since I was 14 back in 1998, and still read & play it now in 2013. So I figure that says something positive about the game. 
I'm grateful that Atlas & the writers hired do such a good job with Ars Magica's products.
Thank you, the reason why I ask is that I would like to own the entire 5th Edition collection as books (not pdfs) as I really love this game, but It is a little steep to buy all in one or two months at the moment.
Goodness no.
Fantasy Flight Games and their (currently) pentad of WH40K-based games.
We're talking purely 2008 and later here.
Oh, I just remembered another book that has been (sort of) announced to be in the works - Last summer's Open Call book! 
That's actually something I've noticed about Ars Magica. Not only do the people writing the books understand the rules from core, they mention relevant supplements and fluff and incorporate them well. They clearly understand what they're doing,the rules, and more importantly to me the cosmology. Its well thought out and consistent. Always having a well thought out cosmology is really, really cool.
Huh. Funny that two companies fit the bill. I don't pay attention to FFG's release dates, just order my Rogue Trader supplements when they arrive. Most of the books have decent mechanics... Most of them. Battle Fleet Koronus's ground combat rules were just... Unworkable. My main challenge to other RPG publishers is if that a small house game like Ars Magica can have 5 rounds of playtesting, their game can have it too.
What is that? I am a new member of this forum and this game, please enlighten me.
Well, as it so happens I was wrong - the Open Call was from the summer of 2011, but the point stands.
Anyway, an Open Call is when Atlas invites Ars Magica fans here on the forum and elsewhere to submit material for the line - in part as a way of vetting new authors. The book I'm referring to was supposed to be a book of adentures in which the featured stories served as an introduction to one of the game's other supplements.
You can read more about its guidelines here: blog.atlas-games.com/2011/04/ars ... -call.html
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