POSSIBLE SPOILER FOR JL
So the latest on the rumour mill is that Cyborg is involved directly in bringing Superman back. Considering we've got almost nothing on the backstory of Cyborg so far, other than his literal creation, the fact he is part Motherbox - I'm rather interested at the idea.
They have a lot of range with the Motherbox technology (I hope they don't go too freelance with it, that could be a nightmare if it becomes a catch all solution) because its very vague at the moment. If it is a living computer, then thats going to be interesting.
I believe the rough outline of the rumour is that Cyborg detects Superman's heartbeat and then figures out that he is in a coma etc. Then brings him to Star Labs, and hooks him up to a sunlight generator of sorts.
Above, rumour.
Below, conjecture as I like thinking about how things might go down.
I actually really like this idea. I can see Cyborg being someone that perhaps appreciated the idea of Superman while he existed (we've been shown that some of the public were shocked at the burning effigies, and that the public mourned his death) and looked up to him. Now that I'm thinking about it, it would be brilliant if Superman had saved Cyborg at some point - just a fly by save, nothing major - perhaps from a car crash...and that would be a nice little "Superman was there for me, why arent you, Dad?" type arrangement with his father, to keep that relationship accurate. Then the accident, then the transformation. After that, recruitment by Bats.
At some point after this, I think a nice reflective part of Cyborg journey would be to visit Clarks grave (I'm going to assume at this point that the JL are informed about transpired events, as there would be no need to hide that from them?) in Smallville when he is looking for a way to handle being different - kind of a "how did you handle being so different to them?" type appeal, as he pays his respects. Just before he leaves...thump thump. His technology registers the heartbeat, just once. It doesn't happen again, but he is suspicious. He disconnects a small part of his new arm, and plants it near the grave, a remote sensor. Later in the film he confesses to the Flash that he doesn't think Superman is dead, and they decide not to tell the others in case they are wrong. The remote sensor picks up another heartbeat some point during the second act, and they decide they have to tell Bruce and Diana, and Lois. They agree to have his body moved to Star Labs, and Cyborg retrofits a machine there to harness and concentrate yellow sun radiation based upon his readings. The third act begins and the major battle is going down, everyone is called away. Critical moment in the battle, things are looking bleak, and we cut back to Star Labs, Superman, slightly longer black hair, unshaven, floating in a fluid that is brightly lit with golden radiation and wearing a Cyborg fashioned solar suit...perhaps with a silver S...his eyes snap open (no heat vision)
Depending on where the lab is, he could be within hearing range of the big battle under in the sewers perhaps? In which case, he wakes up, hears the battle and just BOOMS down into the ground, and burrows his way to the battle (a nice little comic Superman thing we haven't seen in the DCEU yet!).
I have of course massively embellished with my own ideas there. But overall, interested to see peoples thoughts on Cyborg being central to Supermans return. I think it could link in nicely with Cyborgs arc in the film.