Is it possible for the Wii to have games like Bioshock, MSG 4, and GTA 4?

[scottie]

Easily. The Wii uses Dvd's, same as the 360 so no troubles there
If you downgrade graphics then the slower processor is not a problem.
The size of the area that can be loaded at once might be the only consideration due to RAM, but just by reducing the complexity of the textures it can be done