5ever, or until 2024
mearls said:The next iteration of D&D is a game on its own. However, what we’ll do is look at the best parts of prior editions and create either new rules or adapt existing rules to incorporate those things into the game. That’s also a big part of the open playtest, ensuring that the fans of each edition are getting what they see as the most important elements of their editions of choice.
What Is The Next Dungeons & Dragons? - Features - www.GameInformer.com
This has been touched on in many of the threads here, but I think now they have come out and said it. This isn't about bringing back THACO or non-weapon proficiencies or a particular set of psionics rules (or healing surges? or skill ranks? or the warden?), but is about learning from various editions and catering to their fans.