It's too late for the MCU to adapt a World War Hulk movie from the comic book crossover event onto the big screen. There are rumors currently floating around that a "World War Hulk"-inspired film of some sort could be in the works for the MCU. Some are even suggesting that this storyline could play out throughout the next few phases of the MCU and thus make the Hulk himself the new main villain.
The "World War Hulk" event takes place immediately following the events of "Planet Hulk." In the comics, the Hulk is deemed a threat by other superheroes, namely the Illuminati, including Mr. Fantastic, Iron Man, and Doctor Strange and they send the Hulk to space where he can no longer harm himself or others. The Hulk ends up on the planet Sakaar and becomes a gladiator and, ultimately, king of the planet. When the ship he was originally sent in explodes and kills his wife, the Hulk returns to planet Earth to seek revenge on all of the heroes that sent him to space in the first place. The planet Sakaar and Gladiator Hulk have already made an appearance in the MCU in the film Thor: Ragnarok.
Although the events of Ragnarok didn't remain completely accurate to"Planet Hulk," it was still the right time to adapt a version of "World War Hulk" into the MCU. The version of the Hulk in Thor: Ragnarok, where the Hulk is in total control, is the version that seems the most capable of returning to Earth and enacting some sort of revenge on the heroes of Earth. While the heroes of the MCU didn't directly send the Hulk to space, there could have been some sort of storyline revolving around this version of the Hulk resenting the other heroes and how they viewed him as a monster and only used the Hulk when they needed his brute strength to fight bad guys and save the world.
The Timing Is Wrong For The MCU To Adapt World War Hulk
Unfortunately, the time to adapt a proper World War Hulk movie seems to have passed. With Tony Stark's passing, there doesn't seem to be a hero left capable or willing to send the Hulk away, presumably back to space. It's currently hard to fathom what hero would be willing to banish the Hulk. Doctor Strange is the most likely, but it still seems like it would be out of character. Not to mention, the Hulk going back to space would be redundant since he just returned during the events of Avengers: Endgame.
The timing also currently doesn't make any sense because the Hulk has been stable since the events of Avengers: Endgame. Bruce Banner is currently in Professor Hulk form, possessing the strength of the Hulk but retaining Bruce's brain and personality, so it is hard to imagine what could happen that could cause a switch, making him the villain. Bruce isn't even remotely considered a threat by any of the MCU's heroes now, so something drastic would have to happen in the up-and-coming films of MCU Phase 4 and 5. The beloved hero turning bad and presumably redeeming himself seems like an awful lot to happen considering the current state of the Hulk in the MCU.
While seeing the Hulk battle it out with the other heroes of the MCU would be fun to see, the time for it has come and gone. Following the events of Thor: Ragnarok was the only time a World War Hulk MCU movie would have made sense, so now it would seem completely out of place. Maybe something will happen during the events of She-Hulk or Thor: Love and Thunder that will make the possibility of World War Hulk more realistic, but as it stands now, the moment for it is long gone.
