I doubt it. Khan won't even be able to train until August because of Ramadan. So I don't see him fighting Mayweather in mid September.
Ramadan is in late June and will end in late July. Even if it wasn't, Khan won't pass on this big payday for Ramadan, I assure you that.
If it ends in late July, that means he won't be able to train until August. I don't know Khan personally, but I know that people who are as public with their faith as Khan is usually take it pretty seriously. If you're a person of faith, that faith will trump money. Time will tell though.
I think Lara would be two fights away. He would need to be Canelo in convincing fan friendly fashion to get attention, then have a repeat performance on a card in which he headlines. That is a little tougher because he would need to beat a fighter that has a fan friendly backing at 154 and other than Canelo there is no one. There are two many guys at WW or soon to be WW that would put more money in Floyd's pocket.
There are two possibilities for Floyd's next fight: Khan, or the winner of Cotto-Martinez (if Sergio looks diminished, now would be the time for Floyd to take that fight). What Lara does against Canelo is, unfortunately, irrelevant in the short-term as it relates to possibly landing a fight with Floyd.
I really think Lara poses a great threat to Mayweather but the unfortunate truth is that he poses too much of a risk with not enough reward. From my understanding, he doesn't carry nearly the same fan base as a Canelo or Khan. I think Lara's best chance is if he has an amazing performance vs. Canelo that somehow eclipses Mayweather's. It just seems like all the great Cuban fighters coming here generally don't receive the credit they deserve. Rigondeux is probably top 3 pound for pound....but because Arum bad mouths him and his fighting style is little too cautious for fan's liking....he's kind of shut out of the rankings even though he clearly defeated Donaire. It could be the cultural barrier and the fact that many of them don't speak english. I sometimes wonder why the Cubans lack the fan base whereas the Puerto Rican fighters like Cotto are huge. Is it a question of the population of those specific groups here in the US?