Back in 2019, X-Men: First Class screenwriter Zack Stentz revealed that 20th Century Fox was considering a massive crossover film that would've seen the X-Men, Fantastic Four, Daredevil, and Deadpool all share the screen with Paul Greengrass (The Bourne movies, Captain Philips) at the helm.
The film was going to be penned by Stenz and Ashley Edward Miller, and would have borrowed from the premise of Marvel's Civil War comic by having the heroes split into two sides after Johnny Storm goes nova and decimates Manhattan while trying to apprehend Molecule Man.
The project never saw the light of day (obviously), and the success of Matthew Vaughn's X-Men: First Class is believed to be a major factor in the studio's decision not to greenlight the movie. We're not sure exactly how close it came to becoming a reality, but Greengrass has now confirmed that he was indeed in talks to direct the hugely ambitious crossover.
“They did talk to me about it,” the filmmaker admitted while speaking on the Happy. Sad. Confused podcast. “I wouldn’t say I was attached. [We] talked, and I thought about it, and in the end…”
Greengrass trails off here, possibly deciding not to go into too much detail for whatever reason.
It's a shame we never got to see this movie, but now that all of these characters are back with Marvel Studios, there's a decent chance we will get a similar sort of crossover someday.