The problem with that hypothesis is supply and demand is a real thing. First, the bigger schools with more ability to buy out contracts will maintain a massive competitive advantage with the only access to the best coaches by guaranteeing contracts if schools like Syracuse don’t. It effectively forces guaranteed contracts to be the standard. Additionally, if the NFL contracts are guaranteed and college isn’t, colleges would need to pay a premium for coaches over the pros. No matter how much revenue college football brings in, it is dwarfed by the NFL - there is no way colleges will pay a premium for head coaches.
Right now, this very moment - colleges could offer non-guaranteed contracts. They don’t because they can’t without reducing their applicant pool to an unacceptable degree. The only way to get there is for all colleges and the NFL to collude to eliminate guaranteed contracts for coaches - but that’s a prisoners dilemma where the incentive to break the agreement to get a high end coach is so great that it would inevitably happen - almost immediately - and the market would go back to guaranteed contracts.