Man of Steel writer David S. Goyer has said that Warner Bros. wanted Christopher Nolan's Dark Knight trilogy to be part of an expanded universe.
When asked by The Hollywood Reporter if the Superman solo being part of the Nolan-verse was discussed, Goyer, who also wrote on Nolan’s trilogy, said: "Not amongst us when I was doing Man of Steel, or among Nolan and myself. Chris always wanted to keep the Dark Knight films as a separate entity and [the studio] kept wanting, understandably, to pull him into a whole DC expanded universe. Chris obviously was a producer on Man of Steel, and it's tempting to think they were linked, but they really weren't. I mean, I'm sure one could retroactively do it."
The Dark Knight trilogy still stands alone, while Snyder's DC movies form part of the DCEU. His Snyder Cut of Justice League, however, is not considered canon, so upcoming DC movies like The Suicide Squad and The Flash won't be linked to its events.
As for whether there's unresolved storytelling potential with Man of Steel, which could be picked up in a sequel, Goyer said: "I think so. I'm not involved in it right now. I've heard the same rumors you've heard, but I'm not plugged into it. I've stepped away almost entirely from comic book-related projects other than Sandman, which I don't really categorize as part of the normal DC universe. And I'm doing a Batman podcast. I've actually done so many adaptations of comics that I needed a break."
