Since they are working closely with Games Workshop, and GW is fine with this, yes, your concerns don't matter as it's their setting and they can do whatever they want with it.
Long story short, it won't.
Longer version: WoW won't be killed by any MMO. The only way to kill WoW would be Blizzard shuting down the servers. Oh, and GW2 won't have subscription. Don't get me wrong, no subscription doesn't mean it won't be a b…