I think there should be an end to the whole series of editions. Just make a basic core rules set that is easy enough for anyone to play and then periodically release expansions that add new mechanics and complexity that fundamentally alter the way the game is played. It would keep the things fresh without having to re-write the book, so to speak. All expansions being optional of course.
Other than new mechanics, each expansion should include new settings, monsters, magical items, adventures, etc. It should also follow a larger storyline that stretches out over time.
Team D&D needs to take a few cues from those Wizards across the hall.
How long have you been playing magic? You do realize that there have been at least 2 if not 3 major changes to the rules to magic right? Granted they may not have been as big a change as those from 2nd to 3rd edition D&D, but they changed the shape of game play none the less. In the beginning there was Basic Magic (very basic rules), then Advanced (1st ed), then Combat Stacks and Steps (2nd ed), now stackless damage and no mana burn (2.5). The core rule book for magic is hundreds of pages long.
All that aside, I agree that it would be more difficult with D&D to use that paradigm. With Magic, you come out with two new mechanics a year and some card variations to go with them. In order to make money that way, D&D would need to come out with 6 new mechanics for six source books a year. Those mechanics would need to be expanded to fill a source book: multiple new classes, a hundred new feats, new paragon paths and epic destinies, and new magic items. They were already having trouble with the source books they had planned; they combined two books and dropped at least one.
