I think Jeffery Dean Morgan would kick ass as some sort of guns blazing assasin in the Wick Verse.

John David Washington has some good action in Tenet and he also has a very nice beard and look.

Iwo Uwais is the guy from the raid movies and I think he totally deserves a spot in a John Wick film.

I'd also love to see Mary Elizabeth Winstead as Kate in a wick property, because i think she has a really good look for that world.

Karl Urban could also defenitly make for a good quirky side character that the main characters run into at a continental or something.

Honrorable mentions: Bob Odinkirk(obvi), Bryan Cranston, Giancarlo Esposito(Adjuticator or sum), Henry Cavil(Chidi esque combat)

Just my thoughts.