Elder Scrolls Online will kill WoW
Want a surefire way doe doom this game, encourage the developers to think that. Every MMO whose developers have thrown that statement around has fallen flat on its face right out of the gate. And whatever new-fangled feature they try to throw into the mix, always fails to deliver. But then Blizzard comes along, takes that feature and adds it into WoW somehow, and it ends up being gold and they remain dominant.
How do you kill WoW? By taking its customers from Blizzard. How do you do that? You make a game that offers pretty much exactly the same thing that WoW offers, only you do it better. Because the only way to get enough WoW players away from WoW to do any good is to give them a better overall experience. Not as good as WoW... Better than WoW." And I am sorry, but Blizzard has pretty much taken each of WoW's mechanics and taken them to the highest degree. And unless you've got more money than them, and as much time as WoW was in development plus how long it's been out, They are not going to be one-upped.
There are only two MMOs that stand to kill WoW. WoW and Titan.
The best that any would-be MMO developer can do is to design their MMO in SPITE of WoW, not in response to it. While WoW is the elephant in the room you cannot ignore, It should be accepted and acknowledged and development needs to move forward without paying homage to "all-mighty Blizzard".