It'll be anybodies guess. Prior to the Wii (and the DS) Nintendo pretty much did whatever everybody else did (witness the NES -which was basically comparable to the home computers of the time in tech but without a keyboard- and everything after it up to and including the GC/GBA).
It's only really the Wii (and to a lesser extend the DS) where they stepped out of the 'norm' and created a nifty innovative must-have.
I'm thinking Nintendo will try to design it's next offerings to appeal to a similar, but preferably even larger, demographic as they designed the Wii for.
That said, I'm pretty sure the Wii will be plenty for years to come. Especially if they keep adding new control methods for new game concepts as time goes on.







