As I understand it they're proposing the fight happen September 2011. If Khan beats Maidana and one more name fighter in the meantime this would become a very interesting fight. Floyd doesn't have big punching power to one punch KO Khan and the general skill level would be very high. It's nowhere near as good as Pac-May but it'd be a good fight all the same.
Mayweather, and I don't know why you're lost. I'm saying, it's a highly likely Mayweather win, but if May can outclass a taller, fast opponent with a terrific jab, and win every round the way he has with his past opponents, it would say something new about his skills. Simply, has Floyd fought anyone with the attributes Khan has? I'm not saying he hasn't fought someone as good as Khan, that's ridiculous, I'm saying, he hasn't fought someone who is taller, has a great jab, and is as fast as him. Those three sound like a tough combination to shut out. Could he do it? I'm interested.
Even then, I think Khan would be no where near ready. By the end of 2011, his body still would not have made a natural progression into the welterweight division. He'll be nothing more than a blown up 140 pounder, with no proven ability to hang with any 147 fighter, let alone a 147 fighter that happens to be Floyd Mayweather! He should only be challenging him when he's at his own peak. Unfortunately that won't happen until another 3 years, when Mayweather would probably sitting and relaxing in retirement. The timing is not right for Khan, in my opinion. He'll be throwing himself in too deep.
Mayweather vs Khan is a great matchup. I think Floyd would knock him out for sure, but that doesn't mean I wouldn't love to see it.