Injustice 3: 7 Story Directions Fans Would Love
6. Supergirl Resistance
In the Superman ending, the Man of Steel uses Brainiac's technology to take control of Batman and any other would-be enemies, with Supergirl being the only known hero still with free will (despite her being imprisoned).
NetherRealm could set up Supergirl as the protagonist, leading a new resistance after she presumably frees herself. Seeing as all the main heroes are either allied with Superman or under his control, Supergirl's resistance could consist of some of the more cosmic DC characters, as well as lesser-known Earth-based characters like Black Lightning, Red Tornado or even Ganthet.
In the latter stages of the story, Supergirl and her rag-tag team would obviously free the likes of Batman or the Flash, to make sure players less familiar with the DC Universe can play as characters that they actually know.