I think the ceiling on Nico might be out there, but he might be another Jarret Guarantano. Who all coaches said had a high ceiling but IMO he had the same problem Nico has, decision making. Some QBs just out athlete teams in HS and can make all the throws in a controlled practices but when the shells start firing vs SEC the decision making is too slow. Look at Nico in games vs Mediocre OOC teams and Vandy he looked like he was in HS controlling the game and lights out. In all others and the playoffs, he had no control and relegated to a game manager that handed off to D Sampson.
Also, a lot of great college QBs just don't pan out in NFL it's a different game to an extent. I could give you a list a mile long Tebow, Jamarcus Russel, Matt Leinhart, Danny Wuerffel, Heath Shuler, Eric Crouch, Jason White and on and also even NFL guys keep giving Guarantano a chance he has all the throws and all, just don't have it between the ears when the arrows start to fire. As the old saying goes that separates the men from the boys.