I don't see how they could do that. An NIL is theoretically between an individual athlete and the entity that wants to pay him for the use of his NIL. I mean, of course I know that most of these are "companies" supported by alumni who are paying for "charitable appearances". So I guess they could try contracts where they tie the money to remaining at the school - as long as the athlete was performing well. And break the contract for injury or bad performance or bad behavior. But would athletes sign those contracts? The more I type, the more I think that the whole rotten system is going to collapse, sooner rather than later.