Though Superman has been on the big screen many times in the last 45 years, they’ve still barely scratched the surface of his mythology. There is still so much that can be done. Hell, we haven’t even gotten a comic accurate Lex in a movie yet.
There is so much that Gunn can pull from. If Lobo is indeed involved I’m sure there will be some influence from Superman: TAS. Which is totally fine by me. But the Main Man isn’t ever the main threat. He’s hired by the real villain.
I would put money on Gunn finally delivering Brainiac.