The easiest solve is Deuce for Mikal.
When I think about the lineup construction and all the roles people play - in theory Mikal is playing the role of spacer/shooter, on ball/PA defense, guarding the ball handler and wings. In reality he plays help defense and hangs in the corner - he and OG are kind of duplicative and I think most would take OG. What we need is the spacing and on ball defense and the best guy to bring you that is Deuce. You could swap Shamet for Kal in the meantime, but I'm not sure that is absolutely necessary.
The Hart conversation has been a constant, but what Hart does, others do not. Clearly Hart has to shoot and not clog the spacing or allow teams to double Brunson and Kat, but he brings a lot to the lineup that we would lose (rebounding, secondary handling and creation, transition scoring, ability to win 50/50 balls). You can throw Shamet or Deuce in there - Shamet adds the shooting, but can't really help on what you lose with. Deuce brings some handling, 50/50 balls and creation as well as more shooting, so its more of an argument, but I think he's a better swap with Mikal.