Zack Snyder's Man of Steel would have removed the catalyst for several major events throughout the franchise's history.
The DCEU has enjoyed a few successes, such as Killing Zod in Man of Steel was a narrative decision that sparked a great deal of debate, introducing a number of hypotheticals about what Superman could have done differently in the final act of the film.
But what if Superman had, in fact, managed to avoid that final clash with Zod and sent him back to his Phantom Zone prison">Justice League and beyond.
Lex Luthor Wouldn't Be Able To Create Doomsday
Perhaps the most obvious takeaway is that the version of Batman v Superman, as the fight between the two biggest heroes in DC wouldn't have concluded with them needing to work together to stop some common threat.
Batman Might Not See A Need To Eliminate Superman
Throughout Batman v Superman, it's clear that Batman had a vendetta against Superman that quite possibly wouldn't have existed had Superman been able to send Zod back to the Phantom Zone. In the film, Bruce Wayne was in Metropolis during the entire ordeal. It was eventually revealed that someone under his employ was killed as a result of the destruction and in his anger, Bruce held Superman personally responsible. However, the clash between Zod and Superman over Metropolis happened after Superman and the military sent the other Kryptonians back to the Phantom Zone.
Without access to the Phantom Zone Projector of the comics, Superman's only means of sending the Kryptonians back was through the use of their ship's Phantom Drive—a tactic that would only work once. Superman sending Zod with them would have meant he and Zod never fought over Metropolis, thus mitigating some (but not all) of the damage done to the city. Without their fight over the city, Bruce may not have been so wary of Superman. Without the vendetta, the entire core premise of Batman v Superman, while not impossible, would have looked extremely different, and possibly more akin to a rivalry based on conflicting approaches than anything violent. Of course, the absence of violence between Batman and Superman, as well as the absence of Doomsday would, themselves, have prevented other dominos from falling.
Related: Batman V Superman Actually SAVED The DCEU After Man Of Steel
Superman Wouldn't Be Dead In Justice League
Without Batman to soften Superman up, or Doomsday there to deliver the final blow, Superman would likely have survived the events of Batman v Superman. Batman may still have carried the Kryptonite as a precaution—he is Batman, after all—but that's far less significant as he wouldn't use it himself. A somewhat less antagonistic Batman could have easily worked with Wonder Woman (assuming she would still have even been in the movie) to get Superman away from Lex and any Kryptonite he managed to use on him.
Superman managing to spare Zod would have radically altered the course of Batman v Superman, down to its core premise, such that the entire last act would have needed to be changed. Without Batman's violent animosity towards Superman, there'd be no cause for him to use Kryptonite against him. Without the use of Kryptonite, Superman wouldn't have been meaningfully threatened by Doomsday. Not only that, but Doomsday wouldn't have been present in the film. So the only means of killing Superman would have fallen on Lex somehow getting the killing blow, which would have been extremely unlikely in a movie that Batman also headlined. In the end, Superman wouldn't have been dead by the end of the movie, meaning that they also wouldn't have needed to resurrect him in Justice League.
The Justice League May Not Form To Fight Darkseid's Forces
It isn't all good news, however, as several smaller changes necessary to Batman v Superman would have impacted the future of the DCEU in ways that might have delayed the formation of the Justice League. The death of Superman was the impetus for Steppenwolf's attack on Earth, for one. But that could be easily rewritten as Darkseid simply deciding to attack now, entirely independent of Superman's presence. Of course, that would have created a problem as the Justice League revived Clark because they knew that while Steppenwolf was incredibly powerful, Superman could beat him. In all likelihood, Superman could have beaten even the Snyder Cut's more intimidating Steppenwolf on his own, potentially before the invasion even properly began.
With Batman no longer having held a vendetta against Superman in Batman v Superman, he may not have bothered to keep tabs on the other superhumans around the world who ultimately wound up on the team. This would almost certainly have delayed the formation of the Justice League as Superman's all-powerful presence may have had a disarming impact on the world, secure in the fact that the Man of Steel would be around to protect it. However, as easily as he could have defeated Steppenwolf, the concept of Superman defeating Darkseid alone would have been an entirely different story. Had the League taken longer to come together, the world may not have had the heroes necessary to stand up to the Lord of Apokolips quickly enough to stop him. In all, what may have seemed like a controversial but ultimately minor narrative decision to kill General Zod at the end of Man of Steel may actually have been exactly the domino that let the Justice League hold the line against annihilation.
