This can not be disputed. Not Canelo nor Martinez, nor Marquez II will generate more money for Floyd than Pacquiao. If you ask me this irks Floyd. He has worked so hard to maintain his undefeated record yet his arch nemesis who had just lost his last 2 fights would STILL make for the richest fight in boxing.
Canelo would be big but not HUGE. He's big in Mexico but not as a worldwide star such as Pac.
Martinez would be big but would pull in less money than a fight than both Pac and Canelo due to limited Argentinian fanbase along with limited casual fanbase.
A rematch against JMM would draw some interest after his KO win against Pac but given the fact that their first fight was on competitive it also would draw little interest.
The fact that Floyd is still asked by interviewers about the possibility of a showdown with Pac shows that there is still much interest in this fight.