All I can say is "Good luck with that, EA".
WoW is not something any game is just going to measure up to over-night in terms of subscription numbers or appeal. That particular community and market is something that Blizzard has spent years building and cultivating. Further, people have gotten spoiled to the level of polish that exists in WoW today. Unless your MMO offers something mind-blowingly compelling such gamers are willing to suffer through the initial bugs and growing pains, expect your MMO to have a beginning explosion of subscriptions from initial interest followed 3-6 months later by a sudden collapse into niche. That's what I've seen with every MMO that tries to grab or compete with the WoW market.
Also, MMOs have a hideous time commitment requirement, and the ongoing subscription can prove a drain on discretionary spending for some. I don't know of too many people that can manage playing multiple MMOs simultaneously. Honestly, it can be difficult just playing any other game, period, if you are engaged in an MMO. Because of this, I would think the MMO market is an extremely high competition market with little mobility.
Honestly, until WoW finally dies(only two things will kill that beast, Blizzard and time), freeing up gamers' lives to actually play something else, I just don't really see any other MMO ever being more than a niche.
Of course, I could be wrong.