This will go the same way as every other mmo.
It will have new ideas that look amazing. Those ideas will look good on paper, or in previews, but will suck in game.
They will release it too quickly so any hope it did have will be destroyed because people want a nice, shiny, polished game, which wont happen.
They will make their game based off WoW, trying to take things from WoW and make them better, or take things we don't like in WoW and fix them. This never works because new games aren't balanced. They take time. WoW was terrible for a long time after release, and people don't have patience.
Just like all the other very good mmos that have come out, people would rather just pay WoW then wait for the cheap knockoff to fix itself. The sad world of non-WoW mmos. They may be good, but the WoW players are comfortable with WoW. The only thing that will kill WoW will be the next Blizz mmo since the major mmo community trusts them to make a good game.