Well, I was counting on US$50, since no Nintendo game that I'm aware of has ever released for more, and Iwata has spoken out against the $60 360/PS3 games.
Of course, he's also said that he wanted to charge for games based on their content... AND they released Big Brain Academy for Wii at $50, which was kind of a joke...
In conclusion, I have no idea! But I hope they won't break that barrier. Though I know they could if they wanted, and it wouldn't affect their sales much if at all. There's just so much demand for the game they can do whatever they want.