@ OP: I think you make some valid points. The Wii series is pretty tied into the innovation of motion control, and probably won't carry from console to console in the same way that, say, Starfox or F-Zero has.
That said, one thing I don't think Nintendo's ever lacking in is imagination. Even if we can't immediately see how they can build on the momentum of their newly created IPs in upcoming gens, I wouldn't bet against Nintendo. I mean, think about it: looking at the original Donkey Kong, could you imagine that the main character would eventually translate into things like Galaxy, Brawl & Kart?
Besides all of that, I'm not sure that Nintendo is hungering for many new IPs at the moment--they're having a hard time just satisfying the fans of all of their older ones! But if they are, I see that several people have listed things like Endless Ocean, etc., which may not be dominating the charts at the moment... but who knows where they'll eventually lead? If Nintendo sees enough reason to give those kinds of games sequels, there must be a burgeoning fanbase for them somewhere.
