In a new issue of Disney twenty-three magazine (via Comicbook.com), Robert Downey Jr, the brilliant actor who played Iron Man since 2008 talked about how Endgame was the perfect time for them to get off the train and let the mega-franchise go in new and different directions. He said:

Robert Downey Jr also took the opportunity to praise his co-stars Mark Ruffalo (The Hulk) and Chris Evans, basically calling them gems of human beings. When we think of actors that were born to play a comic book character, we think of Hugh Jackman’s work as Logan and we also think of Robert Downey Jr as Tony Stark. Since 2008, Robert Downey Jr has delivered one stellar performance after another in the MCU, bringing not just charisma to the table but also nuance and vulnerability. Over the past few months, there have been a ton of push for RDJ to receive an Oscar nomination for his work in Avengers: Endgame.

Avengers Star Robert Downey Jr Talks About His Departure From the MCU - 94