First off, welcome to the forums!
Second, I take issue with your first "con." To the best of my knowledge, there are very few "hard core third party games" for the Wii right now, and of those that have been released most of them have done pretty well for themselves.
That having been said, I think the game will do well because it is, as you say, an exclusive game in a genre which is underserved so far on the system, but it won't sell anywhere near three million. Also, the audience this game will likely appeal to are the type that buy games shortly after release, so I don't expect its legs to be all that long.







