Nintendo's Shigeru Miyamoto did give a few hints on future plans in an interview in the latest issue of Famitsu.
First, the Balance Wii Board, the peripheral that's included with Wii Fit. The magazine noted that Wii Fit has been quite the success story for Nintendo so far. To this, Miyamoto responded that if the game sees success overseas as well, Nintendo may end up releasing separate titles that make use of the peripheral.
The magazine also asked Miyamoto the inevitable question about sequels, and he gave the expected answer. In case you have to hear to to believe it, Miyamoto is indeed interested in making a Super Mario Galaxy sequel. He's also thinking about the next Zelda title.