The portal is already changed to once annually. Limit the mobility of coaches, staff, and every other student & employee of the university, or you just want to "save the game" and unfairly single-out athletes? There can be no cap on NIL; the courts are clear on this.
Re: 'stepping in":
1. Congress can grant an anti-trust exemption; I'd rather see college football end than for that to happen. Or give every company an exemption so people wanting to screw players over get screwed themselves. Maybe the light will come on then.
2. Schools and NCAA can stop pretending they're guardians of some holy amateur athletics temple, and collectively bargain. This is what the man you beseech, Danny White, has stated is the right thing to do and past time to do it. This would allow enforceable contracts between all parties involved - players, schools, and NIL entities.