Rather than resurrecting Zod to become the bastard creation that is Doomsday, we probably would have seen Zod again.
Superman, leaving humanity even more softened up for either Darkseid or Steppenwolf to subjugate Earth with the greatest of ease.
And this time, he’d probably be best friends with megalomaniac/fellow Superman hater, Lex Luthor (Jesse Eisenberg).
Superman has taught us anything, Lois Lane (Amy Adams) would have probably died in the crossfire, and Darkseid would already have his hooks in Superman, ready to take control of his mind.