consider the market for this:
This movie won't be like Star Wars, Harry Potter, and Star Trek. In those movies you had two types of people, the hardcore fans that will dress up and show up on opening night, and the normal folks who will be pulled in out of curiousity.
This movie will just encompass that first group. I don't see many normal middle-of-the-road folks going to see this movie. I think it will make money, because after all there are a lot of WoW people out there, but this will be a niche film.