The introduction of the Illuminati in World War Hulk movie way more likely. As Marvel Studios regains access to most of Marvel characters following FOX’s acquisition by Disney, many important storylines from the comics can finally be brought into the MCU. The first major indicator of that will be in Doctor Strange 2, as the movie will feature Patrick Stewart’s Professor X as a member of the Illuminati.
In the comics, the Illuminati is a secret society formed by some of Marvel's most powerful and influential characters. Through schemes and lies, the Illuminati were behind crucial events in the Marvel universe. In the MCU, it looks like the concept will be adapted into something close to a multiversal council that will stand against Stephen Strange's reckless actions.
The possibility of a presence of the Illuminati characters.
The MCU is indeed used to changing core elements of famous comic book stories when adapting them. Captain America: Civil War, for example, trimmed down most of the events that led up to the arc in the comics when crafting the story for the movie, and the Infinity Saga managed to play out perfectly despite the absence of Adam Warlock. Needless to say, the workarounds the MCU had to take to tell 20 years of Marvel stories without ever mentioning mutants or the Fantastic Four is also another great example. Now that the studio has the rights to most of the Marvel characters, bringing in something like the Illuminati and therefore adapting World War Hulk just got a whole lot easier.
It could be Doctor Strange's multiversal Illuminati who are responsible for sending the Hulk, or at least some version of him, off-planet. Although the MCU's Doctor Strange does not know this council seemly led by Patrick Stewart's Professor Xavier, the Illuminati are probably aware of the history and dangers of the Hulk in different realities. Even so, the MCU will have to make many changes to fit the World War Hulk story in the current canon of the franchise.
Taking liberties when adapting a comic book storyline into a film is something very common to the MCU, but when the franchise has the opportunity to use something like the Illuminati to set up a World War Hulk movie things can work out even better. Whether that awaits She-Hulk. Either way, the future for the emerald giant and the MCU as a whole looks even brighter.
