Scott Jennings has a post up in which he whips the dead horse that is the imminent Darkfall release. He says that a PvP MMO can't work, people will realize they hate it, and will then scurry back to whence they came (PvE).
He is wrong.
What WILL not do too well in today's market is a 'hardcore' PvP MMO, where people can grief the pants off each other (literally). Such games are
a) Not indicative of the success in general of MMO's that focus on PvP
b) Almost always riddled with various other problems, as Scott mentions but somehow brushes aside (bugs, crashes, lag, or horrible combat systems never designed with PvP in mind)
So, could we all please stop QQ'ing about how nobody wants to play an MMO that concentrates on PvP. It's just like the people that QQ that no MMOFPS can be successful because Tabula Rasa and Hellgate failed (hint: both awful games for other reasons completely).
I know that the Scott's and Tobold's of the world want every game to be exactly like WoW, but in that case they should probably just go back there. That is all.