I think this is pretty much in line with what most people think in regards to the Batman Knightmare scene from Batman Vs. Superman that hints at Darkseid with the omega symbol and the parademons.
Jay Oliva, who directs some of the WB animated films and worked on both Man of Steel and Batman Vs. Superman as a storyboard artist, compares the scene to something out of DC Comics’ Flashpoint Paradox. The long story short is that time travel in the DCU doesn’t necessarily directly change events, but creates alternate timelines which may or may not eventually happen.
“You want to know the answer? Okay… you’ve watched The Flashpoint Paradox, my movie, right? In the DC Universe in the comics, there’s this thing where– it’s a little different than the Back to The Future thing where you can go back in time and change your threads and stuff, but in DC, when you go back in time you create this kind of ‘Time Boom’ kind of thing where lots of things change.
“Okay, so let me just tell you this. Again… I don’t know if this is Zack’s thinking, but this is mine: what if that isn’t a dream sequence? What if what you saw was a Time Boom, a latent memory from the future when Flash comes back? If you look at the cut, he doesn’t go to sleep! He’s waiting for the [Lexcorp file decryption] and suddenly this [Knightmare sequence] comes in, and he’s jogged out of it seeing his own death. And what does he see? He sees Flash. And if you’re a DC fan, you know what’s happening. You know that Flash going back in time, that memory is now coming back to him… mind you, it’s jumbled.”
Obviously, the Batman Knightmare sequence may not directly happen in the DCCU, but something along the lines (i.e. Darkseid) will.
“Batman v Superman: Dawn of Justice” is directed by Zack Snyder starring Ben Affleck as Batman, Henry Cavill as Superman, Gal Gadot as Wonder Woman, Amy Adams as Lois Lane, Laurence Fishburne as Perry White, Diane Lane as Martha Kent, Jeremy Irons as Alfred, Jesse Eisenberg as Lex Luthor, Ray Fisher as Cyborg with Callan Mulvey, Holly Hunter as Senator Finch and Tao Okamoto as Mercy Graves.
Fearing the actions of a god-like Super Hero left unchecked, Gotham City’s own formidable, forceful vigilante takes on Metropolis’s most revered, modern-day savior, while the world wrestles with what sort of hero it really needs. And with Batman and Superman at war with one another, a new threat quickly arises, putting mankind in greater danger than it’s ever known before.