I would love to see WotC put out a 300 page book that contained all the major playstyles in it.
They could devote 10-20 pages to each playstyle, teaching DMs how to run that sort of game, create worlds to fit the playstyle, and put in rules additions, substitutions, and subtractions to aid the DM in achieving a good version of that playstyle for D&D. Doing that would not fracture the player base, since no matter which style you pick, you're still playing D&D and would still want the new monster books, settings, adventures, etc. that you would have without a book on playstyles.