They can but they absolutely must not be allowed. If Nintendo dominates their console, 3rd parties will have to go the Xbox360/PS3/PC trifecta. Therefore, the only companies that'll thrive will be the ones that can make a Metal Gear Solid, Final Fantasy or a Halo. All the others will build another generic FPS or go downhill.
So far, third parties have been using slings to fight with tanks (Nintendo games); they needs to bring their big guns onto the Wii to fight against Nintendo, they can't back off.
My themeforest portfolio:







