Partially by necessity, with actors moving on to other things, and partially by design, Marvel’s Phase 4 will usher in a new era for the MCU-- an era where Marvel Studios will not be able to rely as heavily on established fan favorites. New characters must be introduced and connect with audiences to grow this franchise and carry it forward and The Eternals is a major part of that. Kevin Feige clearly sees the Eternals as some of the characters that can help carry the torch now that Captain America, Iron Man and soon Black Widow, have moved on.