[Hopefully by now this goes without saying, but if you still haven’t seen Endgame, spoilers ahead!] Saying that Hulk went through some transformation in Avengers: Endgame would be putting it lightly. To start with, Avengers: Endgame introduces us to “Professor Hulk” in Endgame. While the MCU doesn’t formally refer to him as such, longtime fans know this is a nod to the original comics. It also opens all sorts of possibilities for where they could take Hulk in Phase 4 and future Marvel Cinematic Universe films.
Writer Peter David and artist Dale Keown created Professor Hulk , and hefirst appeared in Incredible Hulk #377. This issue saw psychiatrist Dr. Leonard Samson working with Bruce Banner to overcome the childhood abuse that gave birth to the various Hulk personas. The result was an apparent merging of these personas into what Bruce saw as an idealized being, possessing the best traits of Bruce Banner and his green alter ego.
What Did Joe Russo Revale about Hulk?
Near the end of the Avengers: Endgame, The Hulk uses the Infinity Gauntlet to bring back those that had been snapped away by Thanos. This leaves his left arm blackened and damaged. He still appears to be injured at the end of the movie as he was wearing a sling at Tony Stark’s funeral. In the comics Banner’s alter-ego has a healing factor, but not everything in the MCU is apples for apples.
Recently, Endgame co-director Joe Russo was quoted saying the following:
“He’s lost an arm…that’s not coming back, he’s damaged himself. It’s permanent damage, the same way there was permanent damage with Thanos. It’s irreversible. As you may notice, his arm is skinnier, it’s blackened. So, he loses a lot of strength there.”-Joe Russo
The Russo Brothers are not scheduled to write or direct anymore Marvel films at this point, so this just may be conjecture on his part. However, he seems certain that this is a permanent injury to The Hulk. Damaged or not I hope we see more of the “big guy” in future MCU installments.