I think you might be right that Feng Shui probably doesn't require a new edition. The rules are clear, the plot is juicy, and the game play is fun. Not a whole lot more that you could ask for in a game.
I find it dissapointing to see what d20 is doing to the standard gaming diet. Though I am thankful that my group still plays a variation of systems, it is getting harder and harder to encourage newer players to take a leap of faith and learn new mechanics.
How would I imagine a new edition would look?
Main Book - Everything a player needs to play. Term explainations. All the character templates that have been added to the game (ideally with 2 page layouts to describe what makes them different in each juncture). All the mechanics and schticks in one place: Guns, Driving, Creature, Magic, Hardware, Arcanotech, and Group too. Essentially all the rules to date. Hopefully there would be less cross-referencing and more examples.
You can't forget the colour information too. But I'd keep it down to a description of what starting players might now about each of the junctures. Keep it broad-strokes so that a player can properly decide if they would be from the '69, 1850, '96, '56, Netherworld, or the Underworld.
GM's Book - There have been countless times I wished my players had not read about Fast Eddie Lo, the Four Monarchs, and even the Lodge. Thankfully, my wishes have been granted for the most part (so far). It would be good to remove the temptation of the "forbidden fruit" from the player's book. This would have a good explaination of how to build GMC's with a variety of examples, where the meta-plot is and where it's going, general faction information, lots of information about the acutal Sites.
Faction Books - Dragon, Hand, Lotus, Jammer, Architect, Monarchs, and Underworld. Here's where the plot really moves forward. In the last books, there were goals mentioned - - which ones have succeeded? Which ones have failed?
Players Options - I've found that Iron+Silk gets used pretty often at our table. There are a few odd things that have come up that have needed to be ad-libbed, but it's been a great guide for that too.
One Big Adventure - Having a few small adventures is one thing, but to have a full campaign for new GMs to cut their teeth on, and old players to see new tricks from, would be great. It's good to see how the writers of a game wrap all the details together into a full story with sub-plots and running gags. Sometimes it's just nice to take the pressure off of being creative for a few months.
These are just some ideas. But my pet-peeves still remain the same. I end up cross-referencing between too many books. Reading the player creation rules isn't as easy as actually making a character. I don't know how much different a new edition would be in those regards, but hope that ultimately the game stays alive.
Gee, I didn't mention what shouldn't change. Keep the dice system, it helps the action remain fast and furious. I enjoy the looseness and creativity of the game.
Still looking forward to the Abyss,
Neil.