They don't need to change the controller. The pro controller is excellent. I've always felt they should drop the gamepad though. WM + Wireless nunchuck should also be included in the box. Like the nes had the zapper and the now standard controllers. Make the GP like Wii Fit; optional.
The GP is exclusionary. Polar opposite of the wii remote. Remains baffling as to why they went in this direction. Like Malstrom said, imagine apple started putting buttons back as standard for iPhones.
Bet between Slimbeast and Arius Dion about Wii sales 2009:
If the Wii sells less than 20 million in 2009 (as defined by VGC sales between week ending 3d Jan 2009 to week ending 4th Jan 2010) Slimebeast wins and get to control Arius Dion's sig for 1 month.
If the Wii sells more than 20 million in 2009 (as defined above) Arius Dion wins and gets to control Slimebeast's sig for 1 month.