What if the coaches have to honor their contracts as well as the universities? If coaches leave early, have them sit out a year or go to FCS which is the same as players. If a university signs a coach to a 4 year contract they have to honor that. If the university chooses to fire a coach prior to the 4 year contract then they risk the recruits under that coach leaving with no penalty.
All held accountable and the players know what to expect from their coaches.