No chance in hell does Khan see the final bell.

People say "Well Mayweather isn't a big puncher". Well, he doesn't have to be. When you fight Mayweather, you are going to be taking a large abundance of quick, FLUSH, accurate power punches. Floyd is obviously no Julian Jackson, but they add up and take their toll. Khan being a smaller man with a HIGHLY suspect chin, I don't think he'd see the end of round 6. Floyd would take a lot more risks against the smaller man and put him away rather early IMO.