Gimme a second.
Tony Stark's enemies weren't some supernatural and unrealistic creeps. They were all realistic? and based on facts.? Even though the first 2 iron man movies were realistic that character was recruited into the Avengers movie which was completely different.
If marvel was able adapt a realistic character like Iron man into the unrealistic world of Justice League why not the Nolan's DK Batman? in the Justice league movie?
Thumps if u think that would would be epic