Marvel: Avengers has the potential to become the spiritual successor to Ultimate Alliance 2. Even though Ultimate Alliance 3 failed to meet expectations and Marvel: Avengers does not allow players to switch characters mid-mission, the potential remains. Marvel: Avengers was designed to last for years before sequels are necessary, so they need to do more than they have done so far.
I don't necessarily think the game is bad; it has a similar feel to Ultimate Alliance and a good story. Most of the problems lie in the lack of content and the repetitive nature of the game. The developers have added new missions and DLC based on different characters to save the game, but they are boxing themselves in.
Marvel should branch out from the MCU Avengers and add lesser-known Avengers, such as Wolverine.
As opposed to focusing on the main Avengers, players should see how the game has affected other Marvel teams. Disney will probably try to make X-Men and Fantastic Four video games now that they own Fox, so this is the perfect way to get people excited. In that case, Disney should be hyping up future X-Men games.
Why should Wolverine be in Marvel: Avengers
Note: We're overlooking Deadpool in this case, and he doesn't meet the requirements to be in Marvel: Avengers, since he is nowhere near rated T for Teen. For this part, pretend he doesn't exist.
Thanks to Hugh Jackman, Wolverine stands out from the rest of the X-Men in terms of marketability. The Wolverine is by far the most recognizable X-Men and has the most considerable following among all of them. Even Fortnite recognized this when they added Marvel to their game, so why shouldn't Marvel capitalize on this?
Having Wolverine in Avengers would boost the game's fan base and arouse interest in an X-Men video game. Although X-Men Destiny didn't do very well, X-Men Legends shows the potential that the games could have today. Disney can set up the framework for a future X-Men game today if they wish to make one in the future.
Wolverine was an Avenger at one point, so there is no reason he could not be a part of Marvel: Avengers. It isn't for lack of support either, since this Reddit post shows just how much fans would love Wolverine in Marvel: Avengers.
Marvel has the option to add comic-inspired Avengers based on the MCU movies, but they may gain more fans if they branch out beyond the MCU movies. Otherwise, Marvel: Avengers may feel like a movie video game rather than a standalone game.