Here, try this:
The Wii is a fad. Just like the Hula Hoop or the Chia Pet. That doesn't mean that it won't sell and make trillions of dollars. It just means that it doesn't push forward gaming in any significant way. The great games of the near future will be driven by advances in physics, networking, and AI. Waggle is a fun distraction. It's like the 3D movie craze of the 1950's; cool technology that isn't good enough for general use. I have no doubt that motion control will eventually come back in a mature form versatile and precise enough to control any type of game...but for now it's just a novelty. Admit it: aren't you a bit tired of playing games with waggle already?
The only thing the Wii could do is cause another gaming crash. Ultimately gaming is a business, and developers will shift resources to take advantage of the Wii's success. The problem is, the soccer moms who are driving Wii sales may tire of it just as quickly as they found it, and Nintendo could end up burying piles of Wii Fit 2 in the desert.