Todd Mayo's brother makes $10 million a year. You think Todd's like, "Hey Buzz, I left you hanging for a semester, and for a half, and for a game, and for a summer. Let me make it up to you and pay $35,000 this year so I can open up an opportunity for someone else to come in and challenge me for minutes and I can prove to you I've learned my lesson despite these other high major D1 coaches not only offering me a full ride but also their booster and handlers offering me some cash/gifts. I don't need those things, my family's got money." Haha, nope.
You're probably right about Mayo not coming back as a walk-on to preserve a scholly for somebody else. I wouldn't if I were him. But ...
Even if O.J. made $10 billion or $10 trillion it wouldn't affect Todd's ability to get need-based aid unless O.J. was Todd's legal guardian.
Todd could give up his basketball scholarship, fill out the FAFSA using his parents' income and his own income, and still get aid. Maybe even quite a bit of aid, depending upon his parents' financial situation. Then, when the bill comes for however much he owes, he could just hand it to his brother for payment.
Not that any of that would happen, but it's theoretically possible.