There's a huge market outside of America for a cricket game on Wii. It'd be hard to imagine that no one ever takes this one up. But I don't know if Nintendo would take that leap, so it may be up to a third party.
Wii Golf - if this were to be inclued on a Wii Sports 2, or as a standalone game, the one big thing they could add is more courses. I know the nine holes in golf blindfolded now.
Hockey could be good, but they'd have to get the controls right. There's a lot more to the game than just flicking a stick.
Want a weird idea for a game that could be made to work with the Wiimote and nunchuk? Lacrosse. Done right, it could see a lot of fans, new and old.