There is nothing left for Floyd Mayweather, Jr. to prove. The only thing he stands to accomplish from over-extending his career is suffering a Manny Pacquiao-like defeat.
That would delight most of his detractors, but unless it comes at the hands of Pac-Man, it won't significantly fatten his wallet. Mayweather already has a deal in place to fight on May 4, and the opponent is believed to be Robert Guerrero, per ESPN.
Guerrero is a solid fighter, but the chance that he will beat Mayweather is slim. The bullying style he employed against Andre Berto won't work against Money, but Guerrero is quick enough to make it interesting.
Mayweather is 43-0 with 26 KO, but as great as his career has been, he's still 35 years old. Not even Money can defeat father time. If he fights long enough, he will be Pacquiao'd.
It may not come by Pac-Man's hands, and it may not be quite as gruesome, but conceptually it will happen.
How many more fights should Mayweather have?
Juan Manuel Marquez's vicious right hand may have effectively shortened both Pacquiao and Mayweather's career. Seeing such a great fighter crumbled in mere seconds was a harsh reminder at how cruel this sport can be to its icons.
Because of Pacquiao's devastating defeat, some of the appeal of the super-fight with the Filipino legend has waned. Without the major push for that fight, there aren't any opponents on the current landscape that even add significant shine to Mayweather's resume.
You can never satisfy those that have decided to hate you. If Mayweather is looking to silence the critics, it'll never happen.
If he fights and defeats Guerrero, he'll be 44-0, and he'll still be regarded as the premier fighter of his era. There is only one way to go from there.
Mayweather could retire from the sport with all his faculties intact, and despite his lavish spending, there is no reason he shouldn't remain a very wealthy man.
At this point, he has won at the boxing aspect of his life, there is no reason to fight until he loses.