I hate how people say that the when you get a quest to kill someone that they die in the story line... Lets not forget that in WoW things can go either way sure sometimes they get beat and sometimes they dont however I dont think that WoW will affect the lore or storyline in the long run. If they ever make a Warcraft IV I believe many of the things you may be successful in doing in WoW wont turn out the same way in the storyline