Well, it could sell that many if Nintendo installed a self-destruct chip in every unit that was set to go off sometime next year. I know I would buy a replacement if mine went (especially with all the new colors available). I wouldn't even care that Nintendo made mine die ;)
My End of 2008 Hardware Predictions (console only):
Wii : 50 million
360: 28 million
PS3: 24 million
These predictions were made on January 3rd and won't be revised