Nintendo employs many western developers, including but not limited to:
Retro Studios, Monster Games, Next Level Games, Kuju Entertainment, n-Space, etc., and used to work with several others such as Left Field, Factor 5, Argonaut and Rare.
Employing others certainly wouldn't hurt, in fact getting as many developers from anywhere in the world to make Wii U games would certainly be a good idea. But while I think you'll see plenty of "realistic" games on Wii U, you have to ask yourself just how much of an impact on the so-called "hardcore gamer" crowd that does not already like and buy Nintendo products, would it actually have for Nintendo to make "realistic/hardcore" games? To me, it might just be pandering to a crowd that is going to ignore you anyway, which from a certain point of view could just as well be considered "selling out" their traditional values for nothing.







