Silva should move up and STAY at Light Heavyweight.
There is nothing left to prove at MW, and I think it's a "joke" that Vitor Belfort might be his next fight. To my understanding, Silva has 3 fights left in his contract with the UFC. Fighting Belfort is a "waste" in my opinion.
I think Silva could beat Rashad Evans, Thiago Silva, Shogun Rua and of-course, Randy Couture.
Silva (vs) Machida is the match to be made. Too bad, it will never happen. (Unless you own UFC Unidisputed 2009 for the XBOX or PS3