Nintendo, but NOT because of momentum. Brand recognition doesn't do anything. Momentum didn't save the PS brand either.
I'm 88% sure that Sony and Microsoft won't have the guts to seriously invest in something what they believe to be casual/inferior/stupid. They are in their own little world of geekyness
If the other 12% happens, it is still Nintendo that has the most powerful financial rescources to be used in the console wars, and they can use them to eliminate a serious counterattack.