Now that director Zack Snyder's sequel to his Superman film Man of Steel - unofficially dubbed Batman vs. Superman - has been pushed back an additional 10 months for development, we have to wait even longer to see the film and learn what is fact and what is fiction, where it concerns a movie that will serve as the next (and, potentially, most pivotal) chapter in DC's shared universe.
However, with Snyder out promoting this March's comic book movie "side-quel" 300: Rise of an Empire - which he co-scripted and produced - that's given the press a new opening to pick Snyder's brain about his Batman/Superman crossover. If nothing else, this may help rein in some of the more outlandish rumors out there, like those involving the newly-announced Lex Luthor (Jesse Eisenberg).
When Batman vs. Superman was announced at the 2013 International Comic-Con, Snyder had Man of Steel costar Harry Lennix read a famous quote from Frank Miller's The Dark Knight Returns comic book. In a more recent interview with the French Magazine Popcorn (via CBT and CBM) about Rise of an Empire, Snyder provided a bit more insight on the connection between his new movie and Dark Knight Returns (note that the following is a rough translation):
"[The] comic book will influence the history of Batman Vs. Superman, on which the writer David S. Goyer and myself will work.”
For those who have neither read Miller's comic nor seen the two-part DC animated film adaptation, Dark Knight Returns revolves around a 55-year old Bruce Wayne, who has hung up his cape and cowl and retired after years of battling crime as the masked vigilante Batman. However, rising levels of violence and unlawful conduct in Gotham City inspire Bruce to resurrect his Caped Crusader alter-ego and return to action - something that not only prompts his most dangerous foes to get back in the game, but in time puts the Dark Knight at odds with the U.S. government and its "ally" (or "lackey," as seen through Bruce's eyes), Superman.
Between Superman's (Henry Cavill) shaky relationship with the government at the end of Man of Steel, 41-year old Ben Affleck being cast as Bruce Wayne/Batman, and the confirmed addition of Wonder Woman (Gal Gadot) - who may be joined by additional Justice League team members at some point in the film - it's safe to say that Snyder's new movie won't be a direct adaptation of Miller's Dark Knight Returns storyline.
However, you can see how Miller's comic might inform the script by David S. Goyer and Chris Terrio (Argo), by featuring an older version of the Caped Crusader who returns to the spotlight, in part because he is extremely distrustful of the alien from another world (and with good reason). Furthermore, when it was published in the 1980s, Dark Knight Returns was heavy on relevant political overtones; Man of Steel likewise boasts a good deal of subtext drawn from the modernized tweaks to the Superman mythos, so it's a fair bet that Batman vs. Superman will also heavily feature updated social/political themes.
During the same interview, Snyder also re-iterated what he's said before about Affleck playing Batman:
“Ben brings an interesting counterweight to the performance of Henry in the role of Superman. He has the experience necessary to paint the picture of an older and more advised man than Clark Kent, who bears the scars of a seasoned vigilante while retaining the charm that Bruce Wayne deploys when present in the world.”
Like this description of "Bat-fleck," certain Batman vs. Superman rumors - like how Bats uses drone technology - fit with the idea of Snyder's film being informed by - but not firmly based on - Dark Knight Returns, while others - see: Bruce Wayne thinking he can resolve his issues with Superman peacefully - seem all the more unreasonable, in that context. Indeed, for now it's safe to dismiss any future claims that suggest Snyder's Man of Steel sequel will involve a Caped Crusader who is not like the version depicted in either Dark Knight Returns and/or Alex Ross and Mark Waid's Kingdom Come comic book (which might also be informing Snyder's film).
Batman vs. Superman is currently scheduled for theatrical release beginning on May 6th, 2016.