Not any D&D that actually looks and feels like pre-4e D&D, anyway. From 0e to 3.x, all of it's OGLed.
Any "Ultimate, Modular Edition" of D&D, is going to ooze OGL rules and terminology.
2. They Can't go for the Instant Kill!
Consider this quote from Mike Mearls:
"We plan to continue offering people access to tools like the D&D Character Builder and the D&D Monster Builder to support 4th edition. We're also exploring ideas for conversion tools so that some of the 4th edition characters and content will be playable with the next edition."Some.
In abandoning 4e, they're taking a huge risk! While lapsed gamers, coming back to a familiar D&D is no doubt part of their overall plan, they've got to, but got to get PF player's to buy their stuff!
And, while comparatively small, OSR dollars are no longer something to dismiss. The Astonishing Swordsmen & Sorcerers of Hyperboria Kickstarter, has raised over 12k in just a month of fundraising. In this economy, that's rather telling.
WotC can't expect everyone to just flock to their banner, overnight! They'll get an initial sales bump, but to be sustainable, they're going to have to make inroads. They're going to have to woo their old customers.
Because sure as shit, their going to lose a chunk of their current ones!
3. There Will be No Edition War!
It'll be a matter of selling compatible products. Not enough gamers will abandon their favorite rule-set, for something too different. Not immediately. But, if it's close enough, with add-ons and modules that gamers can use with what they're already playing...
"Our Supplement CZ is absolutely perfect for you Pathfinder guys! It'll really add some nice options and tweaks, you can introduce for your game."
"Supplement O1 will work really, really well, with any Old School game, not to mention our own 5e Base. It's got just enough and just the right kind of material, that DIY DM's will feel right at home integrating it into their campaigns."
"The New Forgotten Realms is completely compatible with Pathfinder! Check out these Prestige Classes!!!"
If it's good. If PF, OSR, etc., gamers like it. They'll pick up more and more. From supplements to adventure modules. Hell, they don't even Have to really switch to the WotC main rule-set(s). But, even if they don't, they'll probably buy it (them.) There won't be an Edition War.
It's going to be a Seduction.
4. All those OGL Publishers!
Will be publishing, anyway. They need to be sporting the 5e logo and producing content for WotC's Game.
5. They're Going to have to Join the Club, if they're going to Take it Over!
"The new edition is being conceived of as a modular, flexible system, easily customized to individual preferences. Just like a player makes his character, the Dungeon Master can make his ruleset. He might say ‘I’m going to run a military campaign, it’s going to be a lot of fighting’… so he’d use the combat chapter, drop in miniatures rules, and include the martial arts optional rules.” - Mike Mearls.
"I'm the lead designer of a project that will likely evolve into a new iteration of the Dungeons & Dragons ruleset. It's meant to be a set of rules that unites all the previous editions, and the players of those editions. It's a big project, and we plan on involving all comers to playtest and voice their opinions, because really, what's the point of designing a game no one wants to play? And who knows better what D&D players want than, well, D&D players. " - Monte Cook.To win back their former base, the new game is going to have to look and feel like D&D.
If they're going to be the Big Fish in D&D again, they're going to have to play in the same pond as the other fish. And then, Eat Them, if they can!
Thanks to EN World, for keeping a handy compilation of 5e related quotes and news.