I think sony might win. Nintendo might introduce a new wii console, but I have a hard time thinking they'll have new blockbuster titles. Sure Skyward Sword has yet to be released, but Kirby just had a game, and I don't really expect any of their other characters getting a new game with a new console possibly on the horizon.
As for Microsoft, they'll probably focus more on the Kinect. For that sole reason, I don't expect them to win. I admit I've never had face time with the Kinect, but it just never did impress me.
As for Sony, I don't know what to expect from them since I don't have a PS3, I don't really follow them too closely. But from what I expect or don't expect from the other two, I think PS3 could win for that sole reason, provided their show doesn't totally botch.