You know what kind of shocks me? A lot of actors/actresses who worked with Nolan... but never really went anywhere huge or significant afterwards. I don't mean this in a derogatory way, I just mean they didn't really "blow up" the way they probably should've, in the same manner as say, Tom Hardy or Scarlett Johansson.
Definitely Casey Affleck. He’s a phenomenal actor who Hollywood has no idea what to do with. I get the sense that he’s picky (and I don’t know if he’s hard up for work after getting MeToo’d, which is a whole other issue), but I think he would work with Nolan again in a heartbeat.
Why not unknown actors? Nolan is already a strong brand. He doesn't need a-list actors. I like the idea following a character with an new unused face. Thats why I like the casting choices from Tenet and Dunkirk. I hope Nolan continues with that.