Chris Evans has been playing Captain America in the MCU since 2011 when Captain America: The First Avenger came out.
It is all up to Marvel Studios and, if they want to play ball, it sounds like Chris Evans may return in Captain America 4 after Avengers 4 brings Marvel Phase 4 to a close.
There are a lot of angles to this but it ultimately looks like Chris Evans is, at the very least, open to returning as Captain America.
In the comics, both Sam Wilson/Falcon (Anthony Mackie) and Bucky/Winter Soldier (Sebastian Stan) have taken up the mantle of Captain America.