If Marlon Brando didn't start to self-destruct in the '70s, what would his career have been like

https://www.reddit.com/r/movies/comments/ahu8s3/if_marlon_brando_didnt_start_to_selfdestruct_in/

Most people seem to agree that Marlon Brando was the best film actor ever, and that in the '70s he stopped caring about acting. Even in the '60s the films he made didn't matter, and it was just The Godfather and Last Tango in Paris that were a bit of a comeback, so you could say that by 1955 he didn't really care anymore either. But it's really after Last Tango in Paris that his career basically ends and he just does strange little cameos to keep himself entertained - Superman, Apocalypse Now, The Freshman, Don Juan De Marco, The Score, The Island of Dr. Moreau, and often it seemed like he just wanted to see what a new actor was like (Johnny Depp, Edward Norton, Val Kilmer).

So if he didn't lose interest in acting or films in the '50s and stayed interested, what kind of career could he have had if he wanted it? Agewise his contemporaries were Montgomery Clift, Paul Newman, Jason Robards, Rock Hudson, Sidney Poitier, Jack Lemmon, Richard Burton, Rod Steiger, Marcello Mastroianni. And then you start to get the people who were a few years younger: James Dean, Peter O'Toole, Steve McQueen, Robert Duvall, Clint Eastwood. And then the next generation of De Niro, Pacino, Hoffman, Beatty, Nicholson, etc.

So what would his career have been like if he was more consistent and didn't lose interest in acting?