They are going to be in the Eternals movie as well. Sersi is a member of that immortal group. The Black Knight ( Dane Witman) is a hero who took over the mantle of his formerly evil uncle. He's been in and out of the Avengers for years, but never became a big name. No clue if they're going to change his back story in the new film.
What if there is no more Avengers thou? Are would ppl be OK with that?