
One Ant-Man star who has appeared in four MCU projects essentially rejected the idea of ever returning to the franchise, meaning that their character's time in the MCU is also likely over. The Ant-Man series of films has introduced fans to a lot of unique characters, including Paul Rudd's Scott Lang, Evangeline Lilly's Hope van Dyne, and Michael Douglas' Hank Pym.
Some Ant-Man actors, such as Paul Rudd, will be returning to the MCU at least for Avengers: Doomsday (Rudd was part of Doomsday's massive cast announcement), but Michael Douglas recently announced that he will likely never reprise his role as Hank Pym in the franchise. The actor appeared in four total films over the course of eight years (the three Ant-Man entries and Avengers: Endgame), but is now content with leaving his character behind.
In an interview with Deadline, Douglas expanded upon his reasoning to leave the MCU. The actor simply said, "I don't think so," when asked if he would act in another MCU movie. He "was excited to do it" for the four films he was cast in, but Douglas admitted to "enjoying [his] hiatus and enjoying [his] life" away from acting:
"I don’t think so. I had the experience, and I was excited to do it. I’d never done a green screen picture before. I did the 'The Kominsky Method' because I wanted to work with Chuck Lorre and try some comedy. But I’m enjoying my hiatus and enjoying my life."
Douglas founded a production company in 1997 called Further Films that he is still very active with. According to the actor, it became "overwhelming" for him to try to juggle both the production company and acting:
"It was overwhelming running the production company and acting at the same time."
Douglas was asked if he would ever return to acting in any capacity, and he left the door open. However, the actor revealed that it would have to be "something good," because, at least as of now, he does not "feel a burning desire" to be an actor:
"Yes, if something good comes up that I really like. But I don’t feel a burning desire. I’m still producing. I still love bringing people together."
What Will Happen to Hank Pym in the MCU?

Since Douglas does not want to return to the MCU, Marvel Studios will have to figure out how to write off his character in-universe.
Hank Pym did not die in Ant-Man and The Wasp: Quantumania, so some would be able to question where he could be if Marvel Studios doesn't provide some sort of answer. It would likely make the most sense to explain that the character died off-screen, as Douglas is too big of an actor for Hank to be recast. It would likely not even be worth going through the trouble to recast the character when his character arc could easily come to an end.
It is worth mentioning that killing off the character would actually fulfill Douglas' wishes for the character. After Ant-Man and The Wasp: Quantumania premiered in theaters and was then added to Disney+, Douglas joined The View to make a special appearance and talk about what had gone on in his life recently.
While on The View (as shared via Facebook), Douglas was asked about his character dying in the MCU, which he admitted "was his request for" Ant-Man and The Wasp: Quantumania:
"[Getting killed off] actually was my request for the third one. I said I’d like to have a serious [death], with all these great special effects. There’s got to be some fantastic way where I can shrink to an ant size and explode, whatever it is. I want to use all those effects. But, that was on the last one. Now, I don’t think I’m going to show up [for another movie]."
Previously, Douglas mentioned that he would only return for a fourth entry in the Ant-Man franchise if Hank Pym could die in that film. Then, he said that he likely would not return for a fourth film at all, and now, the actor seems set to leave the MCU behind him.
Since Douglas has changed his tune a couple of times, it seems more likely that he is happy with staying away from acting. So, it only seems right for Marvel Studios to kill off Hank Pym. That way, he would have a full character arc in the universe, and Douglas' wishes for the character would be granted.
Find out the original plans Marvel Studios had for Hank Pym's death here.