There's not really an answer to this, as it's up to the developer.
I'd assume there will be games where it is optional, kind of like Shaun White's Snowboarding and the Balance Board. The game was produced with the Balance Board in mind, but you can also simply use the wiimote. I think this will be the best choice for developers, so they don't alienate part of the wii base, which does not have the WM+ (or in this specific example, the Balance Board).








