Probably Marvel Studios Parliament. They make all of the decisions for the MCU.

Avengers, Guardians are done and the X-men/FF are still too new and besides some of the X-men/FF are also Avengers members as well.

I think we will always have a new team of Avengers. The name sells itself for films. I know we will have the Fantastic Four soon, but they can co exist with the Avengers like Guardians did.

X-Men are happening soon…I guess. Still think this development might be slower.

Whichever Marvel chooses.

Fantastic Four and the Young Avengerssss

Well it was stated by Kevin the Fantastic Four will be a big pillar for the MCU so maybe it could be the central team

If not The New Avengers

Thunderbolts will definitely get some attention in the MCU in later Phases. I find it difficult to make a film of them without anything planned for the future.

Young Avengers all the way

The avengers