Any fighter who dominates and retires will have people taunting them to come back. People can't seem to accept when a boxer dominates and just want to see any possible chance of seeing them loose. So if Mayweather came back and beat Cotto and Margarito (big possibility, can't see him loosing to them) and retires, later on a new star will come out and taunt him once again and you'll see people go "Oh! This guy would really beat Mayweather" and so on.