I think largely because of NIL, players who turn out to be very good at Mid Majors are leaving for Power 4 teams. The gap between the top 4 conferences and everybody else is growing. Now if you recruit a player and turn them into a very good player with NIL potential you may lose them.What proven Coach is willing to leave their current situations? You want a Coach with experience and a good track record, but the ones that fit that billing are all probably comfortable where they are.
Just like top players from Mid Majors are leaving, i think we might expect top coaches to do the same looking for a Power 4 team. It is no fun developing good players to see them leave from not fault of your own, just the new NIL impact.