IMO the Skrulls introduction was pretty much ruined from the get-go in Capt. Marvel. We had what could’ve been the perfect introduction for a Secret Invasion sub-plot that could’ve ran through most of Phase 4. It actually started off ok: Skrull shapeshifters are running amok through the US Govt. You don’t know who you can trust, anyone could be a Skrull. Then they went and “resolved” the issue and turned Skrulls into good guys for the sake of “shattering expectations”. The whole finding them a homeworld thing was the stupidest idea that they basically just ignored except just to bring it back up to somehow blame Nick Fury for (the guy who doesn’t have a spaceship and can’t fly around the universe at will). They defanged what could have been a great villain group immediately after they were introduced, the villains have always been Marvels weak point.

What they should have done was just not resolved the Skrull thread at all in Capt. Marvel. Everything else largely plays out the same. Maybe they get some higher-up Skrull and take them out, but, with his dying breath… “This is not over… the Invasion… has only begun…” They needed to leave that menacing tone of the Skrulls intact after that movie. We’ve had Skrull cameos throughout Phase 4, Ben Mendelsohn has been showing up all over the place, but the tone was always these friendly offeat cameos, “Oh look, it’s the shapeshifting alien talking about boring things, how funny, he’s just like us!” Like he was in some sort of buddy cop show or something. NO. They should’ve kept the threat alive, slowly revealed other people being taken over or being revealed as Skrulls, kept that part about Secret Invasion alive where you didn’t know who was who. The audience should’ve been questioning the motives of every character and had theories flying all over the place about every character. The Skrulls could’ve taken the place of Loki as the sort of behind-the-scenes agitator that keeps on causing more chaos.

It would’ve been odd to reveal the start of Secret Invasion sandwiched in between Infinity War and Endgame, but Capt. Marvel was always going to be a weird movie anyways, especially since it had almost nothing to do with Infinity War. At least this way they could’ve introduced the next threat to follow the Infinity Saga and maybe given Phase 4 some sort of direction.