Hulk's constant changes throughout his MCU appearances would perfectly allow him to have his own version of Peter Parker's Spider-Verse arc, which Marvel movies not in the MCU, all of Hulk's big-screen appearances have existed within the MCU. However, Hulk has been the Avenger that has changed the most since he was introduced. Some of these changes have been better received than others, but up until Phase 4, they have all been considered part of one single Hulk.
Shang-Chi and the Legend of the Ten Rings.
Marvel Studios and Sony have turned their past limitations into advantages, as the divided ownership over Spider-Man that spawned three different Spider-Man franchises has resulted in the best and most celebrated part of Spider-Man: No Way Home. Despite Hulk's lack of known multiversal counterparts, this seems like the perfect template for a Hulk movie that reconciles all of his past appearances and puts them into one movie where an arc can be seen in quick time. The return of major villains from previous movies and the badly-kept-secret of the returns of Tobey Maguire and Andrew Garfield offered the perfect event for the end of the first Spider-Man's MCU trilogy.
In the comics, the green, ferocious Hulk that fans know and love isn't Bruce Banner's only alter ego. Joe Fixit, Professor Hulk, Doc Green, and Devil Hulk are just some of Banner's split identities when Gamma radiation takes over. Each of them has their own personality and their own powers, and sometimes they can separate from Bruce Banner just like Venom detaches himself from Eddie Brock. This part of Hulk's story hasn't been explored in the MCU; so instead of introducing new versions of the Jade Giant, World War Hulk movie could instead feature the Hulks we have already met in previous movies coming together.
With disappointing The Incredible Hulk, but it would also streamline all inconsistencies in Bruce Banner's MCU journey and bring forth one definitive Hulk.
