If Floyd beats Mosley and Pacquiao, he'll have proved himself as the best Welterweight. Floyd is also getting old and I think in order to protect his 0, he would retire before he lets the young guys beat an old Mayweather and join the list of undefeated world champions.
He should, so the haters can cry that he is undefeated and whooped the fighters they said could beat him. He probably won't though just because there's money always to be made. Hope he doesn't choose to fight too long. After Floyd beats Pacquiao, they are all going to say that Manny was too small, they are already getting ready to discredit Floyds victory even before the fight happens.
Nope. Too much money left on the table if he retires.
A fight with Khan in the UK or US will make him millions. He can make over 30 million fighting Khan.
A fight with Canelo will make him an easy 30 million after Canelo wins a belt and wins against a few legit WWs.
Don't forget about Bradley.
I don't think he'll be able to give it up before he loses. Even if he enters retirement again after beating Mosley and Pacquiao he'd probably come back again.