I will repeat my earlier claim on Khan, he cannot beat Brook, Porter, Bradley, Rios, Floyd, Pac, Matthysse, Chaves, Cotto, Canelo or Thurman. That's 11 I can think of in a heart beat, I'm sure I can find more. He's a B-grade boxer at best. I will be willing to take any bet should he fight any of these boxers.
This. Except Rios and Chaves. I'd favor him because he has a lot of physical advantages and a considerable skill gap, and neither of those guys has what it takes to land the shots.
I think he'd probably catch and hurt Khan and finish him at some point but I think Khan has a good chance early and can catch Thurman and jump on him. I'm not convinced of Thurman's chin yet and Khan's handspeed would give Thurman a lot of trouble.