WoW is not a PvE game. It's got the best PvE game inside it, but it's not just about that. It's also a pokemon game. And a PvP game. And an RvR game. And a guild building game. It's chock full of little things to keep people busy. Like my post before, there's no pure focus in WoW. It's all of those things. Little by little, new games will come out and they won't go toe to toe with WoW. They'll offer the WoW player a slice of the WoW pie that is done better and with more intensity and focus than WoW could offer. You just can't come out of the gate against WoW, offering people everything WoW can today. WoW has had a lot of time to bolt on PvP, faction grinds, mount collecting, pet collecting, etc. Trust me, all that stuff was not there from day one.
Now you are ready to take on a slice of the WoW pie. WAR is doing this, and it's a smart attempt to do something WoW can not do. WAR is all about PvP. Even if WoW spends lots of development cycles on PvP, it won't be as good as WAR. WAR just doesn't have the same PvE end-game to worry about unbalancing. But, why should someone leave WoW to play WAR? That person needs to be able to detach from WoW, and they need to like your niche. The second part is easy. Lots of people got their PvP feet wet in WoW (or DAoC), and they have a desire to play a game where PvP is done right from the first day. But can they detach from WoW? Some will. Many will not.
Flash back to Everquest 2 and Asheron's Call 2. AC2 is long gone, yet AC1 is still up and running. EQ2 is finally grown larger than EQ1. Even companies own succession games can not lure people away from their old games. People are attached to the familiar and they count their high level characters as valuable posessions they can not abandon. It can take a long time to get people to move to a new game.
I hope WAR does well. I would rather have WAR as a PvP option and WoW as a PvE option. I personally feel that PvP has done nothing but ruin WoW as a PvE game. So far, my time playing WAR has been above average and I plan to try it out.
If only I didn't need to join a damned guild.