LOL! Ain't gonna happen. The haters (who are 90% of his buyers) won't be satisfied seeing him lose to a black fighter.
I don't even know who Cuenca is and I've been a fan of the sport for 17 years. Mayweather isn't fighting some unknown, especially not in his last fight.
Floyd has only fought one black fighter in the last nine years - Shane Mosley. He won't fight a handful of them in his last bouts. I doubt he'll fight any. Floyd seems to have drawn "the color line" and decided that fighting another black man doesn't sell. If he gets past Pacquiao, the frontrunners to take him on in his final fights are likely to be Danny Garcia, Amir Khan, Ruslan Provodnikov, the Canelo-Cotto winner ... even Omar Figueroa. Don't expect fights with Quillin, Bradley, Brook, Thurman, Porter, Berto, Andrade, or Errol Spence. I'd actually lean toward Floyd going with Provodnikov this fall, followed by either Pac/Cotto/Canelo 2 (one of them) next May, and wrapping up 2016 with Figueroa (should he win a 140-pound title). He won't stop at 50 fights.