I am no expert on Superman or what D.C. will do with him. I am sure Kal-El will not retire at least in the long run. He and Bruce Wayne and to a some what lesser degree Wonder Woman are the underpinning for D.C. comics. Of course they are experimenting with different takes on the character and should one of those prove popular enough then who knows? At the end of the day he will always be the core Superman. What might happen and has been done before many times is change his back story. Maybe even to a radical degree with the understanding he could always be rebooted back at any time.