Mayweather isn't a dumb fighter, sure he may not know how to read but he would never accept an MMA fight against one of the top fighters in his respective weight division, the only thing that would warrant that is money, and I don't see the UFC wanting to split that paycheck the way Mayweather would want, maybe if it was a Modified MMA fight with no ground game/grappling and put on by Mayweather's & McGregor's fighting productions, we might see a "mma" Mayweather/McGregor card