While I respect your opinion Quanta, I still highly doubt we'll see anything as successful as WoW in terms of MMOs. At least not if everyone's stuck on making casual games. There are far more games out there now competing with each other, most trying to emulate what WoW did, how WoW did it.
WoW released when the MMO market was still somewhat fresh and most games available were catered to niche markets. Blizzard's casual approach couldn't have been timed better, and I think this is one of the main reasons it became so popular.
Today, most everyone interested in MMOs has already played at least one in the past. Because of that, people are picky and know what they want in them. With so many options out there now (granted many aren't even worth mentioning,) it's hard to think that the majority will all flock to one game.
I'm no fortune teller, but judging by current trends, I don't see this happening any time soon, or really ever for that matter.
