Avengers 4 and Guardians 3 Theory

Possible spoilers, who knows.

I'll start this off by saying Civil War was a better Avengers-level movie than Age of Ultron, but it really looked like CW was more of a part 2 to AOU's part 1, kinda similar to what they are doing with Avengers 3 and 4. They were different movies, but both were team-ups that revolved around the events of Sokovia, and they were also only a year apart. Also, I feel they purposely rushed Civil War to make it feel that way. Typically large sequels like that would take 2.5 to 3 years, but we got it just two years after Winter Soldier.

That said, I think they are going to do something similar with Guardians 3. I believe Captain Marvel will serve as the temporary replacement for Adam Warlock in Avengers 4, but I have a suspicion the fight against Thanos will not end there, and that they'll use Guardians 3 (2020) as yet another sort-of Avengers movie, this time with the actual Adam Warlock helping against Thanos. Putting the defeat of Thanos in a Guardians movie also gives Nebula more agency to play a part in his demise, similar to the comics. GotG is where we got our first glimpse of Brolin's Thanos anyway (slightly different looks not withstanding), so I don't think it's too far off to have him die in that franchise.

I'm not saying I've heard anything like this, I'm just giving my gut feeling. Also, if any of it turns out that way, I have a feeling Downey and Evans will not be part of the sort-of Avengers team in Guardians 3, which could mean things may not go so well for Tony and Cap in Avengers 4.