I have no doubt there will be a "Wii 2" in 2012, but I certainly don't think it will be announced at E3. And I would like to remind people to take rumors with a grain of salt.
Rumors about the Wii that weren't true, reported by the gaming media:
-That it would have a touch screen controller
-That it would not have a d-pad or other traditional buttons
-That it would have a "projector" that projected the action in midair
-That it would have a "pressure sensitive" controller (similar to the back touch screen on the NGP, actually)
-That it would use HD-DVD
-That it would launch in March 2006
-That it would have a form of head tracking where you could view the action from different perspectives by moving around the room
I didn't make any of these up, and in fact you can still even find them online, for instance
here at Gamepro from June 2005.