Disclaimer: the information shared in this article is based off of rumors, specifically those discussed in the podcast Pete's Basement and on comics news website Cosmicbook News.
According to these sources, Marvel plans to revive the X-Men franchise by staging an explosive encounter between Hulk and Wolverine, the most popular mutant!
The idea of this battle didn't come out of nowhere. Indeed, it was inspired by the Incredible Hulk comics. In this comic book, Bruce Banner is shot to death, but Hulk survives and gets out of control.
However, for the fight between the green muscle monster and Wolverine to come true, Marvel will have to get around film rights issues.
Universal Pictures still has the rights to the Hulk, and it would be necessary for Wolverine to be the main character for Hulk to make an appearance, similar to how things were done in Thor: Ragnarok!
Still according to these rumors, the estimated release date of this movie is 3 or 4 years from now, so it'll be a while before it is officially announced by Kevin Feige, the president of MCU.