I just don't see it.

You can argue that aside from the casual and impartial fans, for every Mayweather fan, there is another person who is eager to see him lose. The way I see it, if Pacquaio were to somehow become victorious, most of the Mayweather antagonists would have little interest as they will have already gotten their satisfaction of witnessing May lose. Why would they care if Floyd wins the rematch?

Will a rematch sell? Absolutely, but not near to the initial fight