I don't think that MS will win next gen, but I have no idea who will.
Nintendo obviously has a crazy amount of momentum, but they have failed to capture the hardcore market at all. Whether that is a bad thing is a matter of debate. The point is, if either MS or Sony (with the Xbox 720/PS4) manages to get the appeal that the Wii has now, and at the same time, keep their hardcore base happy, they will pwn all comers.
Sony, to me, is the biggest enigma. They don't have a history of repeating mistakes. Just look at Betamax vs Blu-ray. With Betamax, they had a "build it and they will come" mentality, and they spurned technological alliances. JVC et al. did not, and they won easily.
Blu-ray came on the scene, and Sony did everything that they really needed to do, and laid a huge wager on the PS3, and won. That they did so at the cost of their lead in gaming console sales is really not the point. The point is, Sony is willing to take risks, and they do have a history of learning from their mistakes. Also, MS forced Sony to release the PS3 a year earlier than they wanted to. Imagine if the PS3 had launched in December 2007, at 450US$.
<insert awesome signature here>
Essay Pro