I think there will be some. Many are burned out on WoW. Of course, most have them haven't played or been subbed to WoW for a while now, and some friends have told me that the Panda thing won't even bring them back. So, as the word spreads amongst the "already quit" to their friends that still play... I think there will be a decent chunk that will switch to GW2. It won't be drastic like 80% of their currently active player base.... more like 10%... but that's still a HUGE chunk when you think in terms of WoW's numbers. Some of that will be natural "bleed off" that has been going on already... but GW2 will probably accelerate that "bleed off" some, IMO.