I am only hoping here, but, I think he can become someone like Modric, a central playmaker that can dictate the game from deep areas, carry the ball or pass it forward and be dangerous near the box as well, Mainoo is already an excellent ball carrier, his short passing game is excellent as well and probably his strongest suit, and he can also finish in the box when he gets a chance to do so, obviously he will need to vastly improve his long passing and defensive positioning, because he is also a decent tackler and ball winner, he doesn't need to be an athlete (Macalister isn't athletic but he is brilliant in CM with Liverpool), but he needs to improve his in-game intelligence and read the game well.
My hope is based on the fact that he is still only 20 and has the chance to still develop further and be a lot better by the time he is 22-23.