Maybe, maybe not. There's some things that can be done by Blizzard for a new MMORPG that other games have innovated upon but, as much as players really want a WoW2, I'd stake a lot of money it wouldn't be as popular as regular WoW is. Nobody wants another spinoff like EQ2 to happen. WoW2 would have to thread very very carefully as not to upset WoWs playerbase, and they're an extremely finicky group by any games standards. Change models? Uproar. (a big reason WoW2 couldn't be successful). Change the way game plays. Uproar. Change nearly anything and there's an uproar.
What they could do is update how questing works, how pvp is handled vs. pve. Revisit popular design models used successfully in the past for raids, outside content and go back to a normal story line. There's a reason why TBC and WotLK and to some extent Cata, least until DS happened, were the pinnacle of the game (far as subscriptions). The lore was actually interesting and straightforward, the raids were innovative and fun, pvp wasn't as lopsided and they'll never get pvp to work until they have two separate ways spells and abilities work so one doesn't affect the other. There was actual content for both hardcores and casuals as well as pvp oriented.
They need to stop listening to players when it comes to designing future xpacs as well except for bugs and general feedback. It's because of the players we got WoD. People can argue against this, but I blame the players for the state of the game along with the current crop of developers who're extremely disconnected from reality half the time. Blizz tried doing exactly what players requested i.e. less dailies, less grinds, go back to how it was in Vanilla, another this, do that. In the end we got a gutted expansion nobody enjoys with a phased zone for individual players to stay in all day, every day and a group of devs who thinks they don't need to do anything. Even 6.2 has nothing except a pretty looking zone from what a group of friends told me. Do a couple dailies, get a tiny bit of rep (which was added last minute) and you're done. Silly.