I’ve been kicking some thoughts kicking around my head about the idea that Coulson is appearing in 'Captain Marvel,' and I kind of want to work through them for a bit. It’s all very AoS related, but a little about Coulson’s role on the movie level.
To start with, we don’t know how much Coulson is going to be in the movie; we don’t know how much Fury is going to be in it either. Both of them would have to be de-aged about 20-25 years (depending on just when it’s set), and I suppose that will probably work better in the movie that it did in that one AoS episode but most of the Marvel de-aging magic has been for one or two scenes in a given movie. So while some people think they’re going to be a big part to play, I’m not expecting much more than an extended cameo. I don’t think they’re going to Tarkin this (and even that was only a few scenes).
That said, I find myself wondering why they would bother with Coulson. It’s sweet, and I can see the sentimental reason to go there; but plot-wise, they only really need Fury to be part of it. Establishing how Fury knew Carol is part of her setup to return in A4; and since A4 will probably undo the Snap, there could certainly be a payoff scene between those two characters in the end.
But Coulson? I think there are a couple of potential reasons to include him beyond just being a cool thing to include. For one, I have my suspicions the movie is going to feel like a throwback to Phase 1; maybe including a flash-forward opening (like IM, CA, and Thor), which would allow them to start in space and flashback to how Carol got her powers on Earth. And so, including Coulson becomes part of the Phase 1 feel.
And two, I think it’s likely A4 will reintroduce Coulson to the movie side of things. I think it’s entirely possible that ‘Captain Marvel’ reminds people who he was before he’s resurrected for the non-AoS crowd. I don’t expect the movie to go into five TV seasons of explanation for what he’s been doing; they’ll either pull him off a beach in Tahiti and pretend he’s been retired since ‘The Avengers’ where he didn’t die in the first place (wound took a long time to kill him, but it’s festering; and now someone can fix him; also his girlfriend just disappeared and ...yeah that was totally that cellist he was seeing several years ago,(Nat: Coulson, you’re literally doodling ‘Phil + Melinda 4ever’ on your notebook)), or they’ll bring him back with so many others resurrected in the end and treat it as an anomaly rather than acknowledge that he was one of the Snapped meaning he had been alive all that time.
Depending on how much the movie is willing to work with show canon, there’s a lot of TAHITI stuff that could be explained with the ‘Captain Marvel’ movie. According to my fairly limited research into Carol Danvers she gets her powers from the previous Captain Marvel (or is it Marv-vel) who was a Kree. I would certainly find a way to make the Guest Host body in TAHITI be that Kree. It would explain why Coulson was tapped to direct the TAHITI project, he was part of the group that dealt with the Captain Marvels back in the day. Which means it’s entirely possible TV-Coulson doesn’t even remember Carol depending on how deep the memory wipe went; but that wouldn’t make any sense for movie-Coulson and having him part of connecting Carol to the rest of the Avengers.