I think it will sell like SM Galaxy. According to this site, Galaxy released Nov 3, 2007. By first week of January, it sold approx. 4.5 million. That is what I think Odyssey will sell. Approx. 4.5 million.
Odyssey, as a game, is not terribly different from other 3D Mario games. I expect it to sell like other 3D Mario games.