Even in the wake of his big move to DC Comics, Brian Michael Bendis' business relationship with Marvel appears to be continuing for the foreseeable future.
The comic writer has been hired by 20th Century Fox to develop a script for an upcoming secret project, with Deadpool's Tim Miller attached to direct. No major info on the project has been revealed as of yet, but Deadline confirms it is a new feature film set within the X-Men universe, titled 143.
If the film's name has any significance beyond simply being a working title, it could lie within the comics themselves, but it might not be anything super obvious. For example, 1963's Uncanny X-Men #143 follows Kitty Pryde as she takes on a demon attacking the mansion when the other mutants have all left for Christmas Eve break, but it's very possible this project might not have anything to do with the plot of the particular issue.
143 will be a return for Bendis to X-Men characters; his previous comics work in the franchise includes the New Avengers/X-Men crossover, House of M, as well as All New X-Men and Uncanny X-Men.
Miller is currently executive producing the Sonic the Hedgehog feature film, and directing the Terminator 6. And according to IMDb, he's also attached to direct an "Untitled Kitty Pryde Spin-off" slated for 2019. Could that be 143?