I'm hoping Rhodey will move over to the Disney+ side of things for a while, which would give us 6 Avengers (Falcon, Bucky, Scarlet Witch, Vision, Hawkeye, War Machine) in that corner of the MCU that can do their own thing, team-up on the small screen or join the fight alongside a new team on the big screen.
The main Avengers team on the big screen I expect to be made up of newer members, with Ant-Man, Wasp and Black Panther being the three who will definitely feature.
With Thor off in space with the (As)Guardians Of The Galaxy, Hawkeye and War Machine doing their thing on Disney+, and Tony, Steve and Natasha (prequel aside) all out of the picture for various reasons, that would leave Hulk as the only original member who could still feature on the main team, which would give them a big hitter if Captain Marvel is otherwise occupied with her own story.
I'd say the other three could be Captain Marvel, Doctor Strange and Spider-Man but if those characters are otherwise occupied with their own story then there's going to be Hulk, Valkyrie, Shang Chi and maybe Nova to choose from as substitutes, as well as characters we'll see in Eternals like Sersi, Starfox and hopefully Hercules or Ares.
Black Knight is another possibility if the rumours about a Captain Britain/Black Knight film are to be believed...
(...and from the wishlist, let's have Wonder Man, She-Hulk and Tigra some time soon please)
We don't need to hold on to old team members on the core team, they can have their own story on Disney+ and still show up to fight alongside a new team when needed. That leaves more room on the big screen to tell new characters' stories.