With just one ping to Manny, this match is possible. He's the one that just have to make an action to trigger the fight.
This is possible but least likely to happen, Mayweather is already rich, he has the money and he can fight to an exhibition game and make millions.
He doesn't need to risk his undefeated record, he also wants to have a legacy in the sports of boxing, and even we don't like his style but the record speaks itself that he is a good fighter.
He is living to the fullest and it can change within few moments.
I guess you are right that he's going to value now his record rather than have a fight with Manny again and has the chance to lose his undefeated record. At least he has a good history of being undefeated and once defeated the living legend whom had a lot of world title.