Monster Hunter would not make sense since Monster Hunter 4 is coming out, unless they're making a port for the Wii U, but that's way too early.
Perhaps they're going to surprise us with another Okami? Okamiden, the sequel to Okami, was for the DS and Okami has similar gameplay to The Legend of Zelda: Twilight Princess when playing as Wolf Link. Also, Okami was ported over to the Wii and people said that the brush made sense with the Wiimote.
Hey, I know! Zero from Megaman for Super Smash Bros. Wii U/3DS. I mean, why should Capcom do anything related to Megaman? Just let Nintendo recreate Megaman characters for a crossover fighting game. Why make Megaman games when you can just put them in other games as cameos or guest appearances?
A Megaman on the Wii U and/or 3DS is a slim possibility.
Maybe Street Fighter X Nintendo? Akuma versus Ganondorf! Ryu versus Mario! Luigi versus everyone at the same time! And Samus versus Chun Li! Kirby versus M. Bison! Oh, don't miss Link versus Dan! The ultimate fight begins!
I remember Capcom being involved with Zelda games, so maybe Nintendo and Capcom will do something with Zelda. Capcom has been known for good combat systems so maybe the next Zelda would have a more complex combat system?
New IP(s) is a possibility.