That depends on who you consider their competitors. WoW worldwide is about 50% of the MMORPG market. It will be interesting to see how SWTOR fares in that space. Almost up to 2M subs already,
However if you consider the larger online gaming market I would consider WoW's main competitors the likes of Zynga. Farmville alone has 28.4M monthly active users.
I'm not sure I would consider WoW (a game with a monthly subscription and a 20+ GB client) to be a direct competitor with Farmville (a free-to-play game with a browser-based client). I suspect that they appeal to very different audiences.