I like the assumption that WoW will actually manage something even remotely better... Several MMOs have tried non-Auto Attack systems and almost all of them failed at it...
The reason why Auto Attacking works best is because there's significantly more going on and being processed in an MMO than in any other kind of game. Fighting games are 1v1, so trying to say that a Fighting Game like system will work in an MMO is a bit short sighted. Sure, on paper it works well but there are obvious issues that need to be addressed (like the fact that every MMO has lag, regardless of how good your connection is) as well as the fact that using tons of fighting game combos on one huge monster who's only options for being "difficult" are to either have stupidly powerful attacks and AoE abilities or to be a fighting game style character himself (meaning he can only really target one person at a time.)
Ultimately, the issue becomes that no matter how you spin it the game is going to become button mashy because MMO systems aren't typically optimized for the kind of precision and attentiveness necessary in a fighting game system -- and that's coming from someone who has invested time in learning to play Fighters competitively. Unless an MMO is built from the ground up as an action or fighting game -- I don't see how it can spontaneously decide to switch to a system that "feels like a fighting game."
I'm open to be proven wrong, but I don't see it going over as well as some people seem to expect it to.
I'm sure they'll think of something satisfactory, but I doubt they'll be able to do anything that breaks MMOs away from auto attack systems because as it stands, none of them really work.
EDIT:
That aside, you have more action based systems like Phantasy Star Online and Tera Online that work awesomely, but I feel like -- if they are going to try and shift WoW over to being a game like that, they'd probably just do better making Pandaria a stand-alone game.