It depends a lot on how the game turns out.
I think the style may be putting it in a position such that only hardcore Disney fans and counterculture weirdos will be interested in it. "Epic" seems to mean "Dark" to these guys and "Dark Mickey" is like "Gentle Rambo".
I think the fact that a well-known hardcore game developer is working on it may result in a game that's too complex, too cinematic, too long and too boring for Wii owners that are looking for fast action a la Wii Sports, Raving Rabbids and Super Mario Bros.
If the game manages the problems above it could surpass 2.5 million. My gut feeling is that it will fall into some of the pitfalls I mentioned - if so it should still pass 1 million but it will struggle to pass 2 million.