Untitled X-Men/Fantastic Four (2010s) crossover film

Untitled X-Men/Fantastic Four (2010s) crossover film was a planned film for the X-Men and Fantastic Four reboot universe.

Plot
Unknown

Why It Was Cancelled

 * 1) Fantastic Four (2015) bombed at the box office.
 * 2) Fantastic Four 2 (2017) was planned, but got cancelled.

Result

 * 1) The film was permanently cancelled.
 * 2) The X-Men and Fantastic Four rights reverted back to Marvel Studios.
 * 3) Disney bought 21st Century Fox in late 2017.