The only area Rice needs to improve, and it's vital if England are going to win major honours (unless someone else comes through), is his desire to run the game from deep. Get on the ball constantly, show for it, learn where to move to pick it up. It's the only weakness in his game. I'm basing that on a comparison to Rodri who is the best in the world, so high standards but still something I believe Rice could easily develop.
If Stones can stay fit and Southgate encourages him to step into midfield as Pep does, there'd be less need for him to do it as Stones would do that element. I don't think Southgate will ever let Stones do that though, I think he's much too concerned about a rigid defensive line, which is understandable when Maguire is the leading LCB in the squad.