Agents of Shield started out as a major part of the MCU, by being the “extension” of the universe that we never really would see in the movies. Shield had long been established at that point, and with the revival of Agent Coulson (and appearances from other Shield agents from the movies, including Nick Fury) we had “connective thread” that would ensure that things would be there…without necessarily “being there” if that makes sense.
However, due to the vast changes in “policy” with the MCU, Agents of Shield now is considered a murky part of the canon, or just straight up non-canon. Fans want them to come back, but will they? Iain De Caestecker, who played fan-favorite character Fitz for the series, is fine with not coming back believe it or not:
“I think I would say probably no. And not that I didn’t have a fantastic time doing it,” De Caestecker explained. “I think, after everything that happened to those two characters [Fitz and Jemma Simmons], they really gave them a happy ending. And I think it would be so sad to mess with that again. It’s not fair … I’m not sure they would survive it this time. So I like the idea that they’re living a life of normality outside of the SHIELD.”
Fair enough, and they did truly have a happy ending via them being together and having a daughter. Now, for the big question, is AOS…canon in his mind?
“I would say you might have to, because I think the original conception of the show was the fact that Coulson had come from The Avengers, isn’t it? I think you would kind of have to say it is canon.”
Indeed, you’d think it would be that simple, but sadly, Marvel has made it so that nothing is simple anymore.
Source: Digital Spy