I don't think GW2 will be a WOW-killer but it might be a strong WOW alternative. I really like what I am seeing and think it will be a success.
The truth of the matter is that LOTRO and DDO online both have made more money in a F2Play model than they did as P2P. GW1 obviously made
money with its B2Play formula.
If content comes out every few months that is worth buying, then the game will be successful. I like this model because it pressures them to release something worth buying.