The DCEU relies on the character of Superman, and the rich, deep cinematic universe of stories and characters should not suffer at the hands of the literal most important character's actor departing the role. The only true way to solve this is to bring in the only actor capable of picking up where Henry left off, thus allowing the DCEU to continue: Don Cheadle. Sure he's War Machine, but he has experience replacing superheroes. Speaking of which, if Cheadle says no, just bring in Terrence Howard as plan C.