There's really no one in his age bracket that even compares. DDL is already considered one of the finest actors to ever do it. In that sense he's the only suitable choice if you're going to try and replicate Brando's casting. It'd be hard to live up to that goal otherwise.We know they're looking at DDL for Jor-El, and since no other actors have been mentioned for the part, it's possible he got it. *fingers crossed*
Assuming he doesn't, who else could compare to him in the role?
Incidentally, Jor-El being a relatively minor role and Marlon's previous involvement, would possibly be the closest shot DDL could ever consider this movie. Part of me wants a larger role however, as I would love to see just a bit of Krypton's culture.