Not sure, Stark has had a huge role in the first Spider-Man movie and I still see him acting as a father figure to Peter moving forward.
A Black Widow solo movie is also in the works (Though that may be an origin movie?)
I do see Cap making his final appearance in Avengers 4 though.
I'm also really interested to see whether Gamora comes back to life.
Edit: That Peter Parker Disappearance scene, would have been way more impact full if a second solo movie wasn't already in the works.