IMO AJ's career was finished by Dubois. That's it. Done.I know you are a keen follower of the Noble Art, so I'm guessing your post is somewhat tongue in cheek.
The last defeated challenger to get a rematch was Rocky Balboa, this is so irregular and probably highlights how 'balls deep' Hearn is with the Saudi's.
I actually thought Zhang might get a shot, in light of him destroying Wilder in his last fight, just think of the TV audience in China alone?
If this fight does happen, and I'm not convinced it will, Dubois does a 'Joe Bugner/Richard Dunn' and destroys AJ in the first three rounds, and finishes his career.
This is far more serious than a threat to AJ's "career"; it's a threat to his health and potentially his life. It would be crazy for AJ to carry on after his destruction by DDD.