Leatherhead
Possibly a Idiot.
But let's say they really have accomplished what they hoped to do: Turned D&D into an evergreen game, a perennial classic like Monopoly or Risk - one that abides, with only relatively minor fluctuations. If that is truly the case, a new edition would be disastrous. Why? Because a new edition means re-learning the game and playing a different style of D&D. Now this is something that a lot of diehards like to do. But casual fans generally don't.
I was just at the mall shopping for the holidays, when I looked at the contemporary issues of Clue and Monopoly (the ones that weren't just boxes reskinned with whatever hot media property you can think of), and noticed that they had added new tokens and characters to the games. Which I imagine will the strategy with "Evergreen" games going forward.
I expect that the next true edition of D&D will be a long time coming, but we will revive "Micro-Editions" instead. Not unlike 3.5 or 4e Essentials, but significantly smaller in scale and incorporated into the core book reprints. Nothing bigger than subclasses, and maybe some pruning. Like having a "Wolfbrother" ranger path instead of the Beastmaster. That way the Beastmaster isn't changed, but people finally get their fix.