3. Echo
In the upcoming Avengers Endgame, Clint appears to have taken on his comic persona of Ronin. However, in the comics, he wasn’t the only one to go by that name. One of those people was a deaf, Native American woman named Maya Lopez, who also went by the codename Echo. She has photographic reflexes and is a master fighter. In a world about including diversity, I think it would be cool to see someone like her on screen.
In the comics, she did have a romance with Clint. However, in Avengers: Age of Ultron. It was established that Clint is married with kids. I think it would be cool if they twisted that and made her an ex or sisterly figure, like Black Widow. Maya could also serve as a mentor to Kate after Clint’s inevitable retirement. She could be a bridge between the two Hawkeyes. She could also carry on the Ronin name if they want to go that route.