Fan Casting Superman: The Motion Picture Anthology

What if Alexander and Ilya Salkind never fired Richard Donner from Superman: The Movie and Superman II? In this, let us think about how the Superman movies may have evolved if Donner was allowed to stay on to finish I and II together as intended and set the stage for future cast and crew for the DC Comics and Superman film universe that would keep the essential "verisimilitude" approach that worked for the first film