There's no way to beat a Mayweather with top p4p power IMHO, no fighter could cope with the options such a fighter would have. That being said, he might have trouble getting fights if he damages his opponents too much or makes them look stupid ... who knows?
Doubt having elite power would make much difference to how Floyd fought. His lack of power is a bit of a myth, his modest knockout ratio being down to his cautious style (and frail hands) more than a lack of punching power. Also, as long as he was the cash cow he would never be short of willing opponents, whether he hit like big George or little Paulie.
Pretty much that's what Canelo is. He's got the high level boxing skill of Mayweather along with the heavy handedness of Gennady Golovkin.
A counter puncher with big league power and fast hands is a very difficult proposition for any fighter. You cannot make a mistake. Sergio Martinez, Marquez and Toney were the best examples in recent memory. Three very different fighters but they were all heavy handed counter punchers.
You know it's true. Floyd himself gave Canelo his full endorsement, something I don't think he's ever done with any of his other opponents. He recently said Canelo was the total package while in the U.K., he's picked Canelo to beat Golovkin, even said he would knock him out, he said Canelo is the future of boxing after he fought him. Floyd obviously sees a Canelo as a guy who has the high level skills he has, but also knows he's very heavy handed and has dangerous punching power.
Archie Moore comes to mind. Longest reigning Light Heavyweight Champion of all time. Only he had plenty of losses because back in those days guys fought instead of sparred to keep sharp and in shape, and he fought well past his prime. But if you take him at his peak for 49 or 50 of his fights, out of a record that was 186 (132)-23-10, he could easily retire unbeaten in most eras. (Thought maybe not his own, having to face Burley, Bivins, and Charles.)