1. The iPod stopped selling after the first model, right?
2. You're assuming that they'll simply iterate on the current motion controls and upgrade the technical specs. That's a rather 'birdman' way of thinking (yes, in this situation it applies to the bird as well). The idea behind the Wii isn't 'motion sensing'. The philosophy is 'finding new ways to interact with games'. Their next console will certainly do that, and they sure as hell will have learned what not to do after all these successive generations of consoles selling less than the previous.