As you mentioned, Benzima has accomplished a lot in Real Madrid, but he cannot improve on his performance from last season.
He is not a young player who still has age on his side; he is almost close to retirement, I believe, because he is the type of player who likes to give younger players chances, which is why he was able to win his one and only Ballon d'or, which many people know is his one and only because he cannot win more.
Real Madrid is known as a club that has no tolerance for players who are already old, when a player is deemed unable to contribute anymore to the club, they will immediately sell him or let the player leave when his contract ends. Benzema will not forever be a mainstay of Real Madrid, now that he is 35 years old, Real Madrid has started to look for a replacement for Benzema. I think Benzema will be at Real Madrid as long as his contract remains, after that his time with Real Madrid will end.