I honestly don't get the Caleb hype, but I am not pretending to be a QB guru.
It's what he can do, not necessarily what he has done sometimes Like even though he didn't have a great game throwing the ball vs. Arizona, one play that people have harped on as like a "generational" type of throw, was an incompletion in the end zone.
I feel like Caleb Williams will probably be good no matter what. But good coaching is going to be huge for him. Sometimes it seems like he's fucking around, or trying to play hero ball too much. A good coach would be able to rein that in a little bit. IE not the Bears.
If Fields proves that he's the guy, you keep the franchise QB, and trade the #1 pick for a franchise-altering number of picks and players. Ideally to an AFC team. If there are still questions about whether Fields is the guy or not, you trade Fields and take Caleb Williams #1. And you pair him with the best offensive coaching staff you can find, including a head coach with an offensive background.