There are many characters of Marvel which we will never see in the future. Iron Man had died and Captain America passed his legacy to Falcon. Natasha also died and Barton finally decides to retire, so the plot has not any spots remained for them.
But there are many characters who are still on the course, Thor boarded the ship with guardians and Hulk remained alone. But there is still life left in him and could feature in next phase, But the question is how?.
We have some theories about his possible return to the franchise:
This is kind of reincarnation of Hulk as he is the ideal version of Bruce Banner where he has the all necessary strength of Hulk. Professor Hulk is termed as Professor as he has also the intelligence of Bruce Banner. Normally Hulk is an angry and innocent guy which only aims to destroy his enemies. But this version doesn’t transform Banner to Hulk or vice versa.
After everything happened and Hulk been devastated and when loneliness strikes him on the par level. His more Violent nature will become problematic for him and decides to leave the Avengers and thereafter become which none expected. In also Comics, Hulk also portrayed as a villain, so there will be a chance that remaining Avengers will face more violent version of him.
So hulk can be presented in these ways only or thereafter Marvel doesn’t have any plans to bring Hulk any sooner, so he might be off for some movies in future MCU.