One of the truisms has been that a person, usually young, will come into the gaming world on a Nintendo system, then eventually in a few years, graduate to the more mature consoles, now those of Sony and Microsoft.
With the Wii, new gamers, though not necessarily young, are coming into the gaming world. But they aren't learning on a traditional controller. But on the Wii remote. And if they play on the Wii until the next set of consoles come out, that could be 5 years of learning on just that controller (or the equivalent with extra plastic wrapped around it).
Right now, the previous generation of consoles gamers on the Wii are having to learn the transition from lot of buttons controller to the Wii remote. And it is hard on them. But by the next generation consoles, they will be used to it. And the new gamers will know nothing but waggling your controller.
Where does that put Sony and Microsoft? They will, I think, come out with their own motion controlled remotes, that is, their own 'gimmicks' as some would call it. But their games will be still designed with the analog controllers in mind, since that is where their gamers still are.
Because of this, I think it is possible, that Nintendo won't lose the new gamers as much to the other consoles, cutting them off at their knees to slightly-new users.
Torturing the numbers. Hear them scream.