A new Donkey Kong platformer (a real one, not Jungle Beat) on the Wii would be huuuuuuuuuge.
Bigger than a new Zelda sales-wise IMO. I think a new Zelda could do 8-9 mill on the Wii, but a new DK done well would be 10-12 million WW.
Along the lines of Donkey Kong Country on the SNES. The time is right, that's definitely one franchise Nintendo should look at. I think actually this is what EAD Tokyo has been working on since Super Mario Galaxy finished.
Punch-Out! will be a hit on the Wii next year too. It has lots retro-gaming appeal perfect for the Wii audience.







