I don't agree with you that GGG can't last the whole fight just because of his age. He has the stamina to last long.
But likely, if the fight went to a decision, Canelo might be the winner. GGG can only win by Knock Out or he is evident the clear winner of each round like what happened when Bivol got the unanimous win against the favorite Canelo. Canelo is the current cash cow and the result might get influenced in favor of him.
If there's a manipulation then most likely Canelo will win again. GGG does believe that he will be robbed again if he will not KO Canelo, so it's going to be a hard job for him knocking out Canelo because the champ is a younger guy and still on his prime.
What I expect in this game is that it's gonna be an entertaining fight, but most of us believe Canelo will win via decision.
Would you agree with that?