I don't think WAR will over-shadow WOW in the near future. But it doesn't need to in order to be very successful. I think most WOW players will keep playing their game because most of their friends are there and they enjoy the PvE much more than the PvP. Because let's face it, WoW PvP has taken a nose dive since BC.

Then there are those who enjoy PvP and simply thrive for group-oriented PvP with strategy and a sense of accomplishment. I am one of those players that enjoyed the WoW quests, and the amazing artwork, and the occasional raid. But the lack of quality PvP and guild oriented PvP was a huge factor for me when switching to WAR.

WAR offers RvR which hasn't been replicated since DAOC. WAR offers mind blowing artwork and creativity with public quests. Basically, WAR offers similar attractions that WOW has while offering players with the potential for large scale battles that shape and mold not just the player and the guild, but the whole realm. Finally a player's actions can contribute to the whole game world. This is something that is missing from WOW...maybe WOTLK will change that.