It's no secret that WoW desperately needs another reset/revamp. The old world leveling storyline is so broken and disjointed thanks to so many expansions, that it's a bit of a joke. There are tons of bugs in the old world that never get fixed (just encountered by me, you can't enter the Dark Portal any longer to visit Outland, and must be ported to Shattrath).
With Pandas and Allied Races being opened up to the DK class in the near future, it pretty much confirms for me that Blizz is getting ready to do a reset for the next expansion. Whether this 3rd Sundering will happen due to N'Zoth fall out, a new Scourge invasion, Nyalotha, Void Lords, or any number of other threats, I think we should be ready for a revamped Azeroth to be announced at Blizzcon.