I think the comics, as well as the previous films, give insight as to who the main villain in this movie is going to be. Darkseid and his forces have not only attacked the Justice League and their universe but they also attacked and conquered the “New 52" version of Earth 2. In the original DC multiverse, Earth 2 was the home of the golden age heroes. Jay Garrick Flash and a Superman who was active during World War 2. But when the multiversal reality was reset once again for “New 52”, this new version of Earth 2 differed from the mainstream universe in that Darkseid and his minions viciously attacked the planet resulting in the deaths of that universe’s version of Superman, Batman, and Wonder Woman. The first key detail here being that the Darkseid minion that led the attack was drumroll please, Steppenwolf. The same Steppenwolf who has been confirmed as being a baddie in the Justice League movie. But that’s not all. Steppenwolf was not the only thing besides a near unlimited army of parademons Darkseid had at his disposal to subjugate the entire human race. He also had a corrupted version of the very same Superman of that planet who seemingly had been killed during the initial invasion. So my guess would be that besides Steppenwolf, the heroes will also find themselves facing off against a version of Superman that fully embodies our and Ben Affleck Batman’s worst nightmare of what a truly evil Man of Steel without a hint of truth or justice and a complete disregard for the sanctity of life would be. This would also explain the rumors of the solid black Superman costume and why no big villain reveal in this trailer. As I would imagine future trailers will eventually showcase Steppenwolf but they’ll try to keep Worst Nightmare Superman a secret just as long as they possibly can, which with Snyder means a big reveal trailer a few weeks before it opens. This would also allow Rainbow Coalition Captain Planet Green Lantern scribe Geoff Johns to implement one of his dumber comic book ideas as a crucial key point of the film, that one of the things which make Cyborg super-sized for the Justice League is that he is capable of fairly easily hacking into Apokolips more complex than any of that universe’s most unfathomable alien technology. Which presto chango will magically change Nightmare Superman back into good old regular neck-breaking Snyder Superman.