The problem with a salary cap in college is that technically, these players are being paid by third parties for use of their name, image and likeness. I know, I know, it is being abused and treated as pay for play by many schools. But the court action that started all of this said that the NCAA can't prohibit players from profiting from their name, image and likeness.
A big improvement would be to tighten the transfer portal. Maybe one transfer within four years or else sit out a year. Teams should not have to recruit the same player four years in a row.