Conversation was probably like "Looks like you are only going to get your guarantee for this fight, 32 million. Canelo fight is projecting you to make in the 45 to 50 million range." Sold!
once Mayweather fights Canelo there will be a rematch. so Showtime will make the most money they've ever made. first fight does like 1.5 or even 2. 2nd fight does even better. lots of money there
The 6 fight deal is the carrot. It's the carrot Mayweather dangled out to the public. The public believes there is a finite amout of fights left in Mayweather's career. His fights will continue to draw more and more interest because of this, regardless of who he fights.
Assuming he doesn't lose, can you imagine what his last fight will draw? Especially if he ends up going against another star, say broner (should be in 2 years time).