This is at heart a bunch of legal issues, most of which have been decided by SCOTUS:
-- Can people contract for purposes of earning money? Clearly, the answer is yes.
-- Is there a monetary cap on what they can earn on such contracts? No.
-- Is there any legally-imposed definition of "market value," or any stipulation that the contract has any reasonable expectation of being profitable for the party paying the recipient? No.
-- Does the fact that the person is a scholarshipped college athlete affect any of that? No.
-- Can the NCAA prohibit, or in any way control, those contracts? With the exception of prohibiting member institutions from contracting directly with the athlete, no.
-- Can a person go to college wherever he or she can gain admission? Yes.
-- Does the fact that the person is a scholarshipped athlete change that? No.
-- Does the NCAA or any other organization have any control over any of these circumstances? No.*
* Possible exception is, in the event of a transfer, requiring a waiting period before being eligible to participate in competition, though even that isn't clear. For now, the NCAA has abdicated control, and there is no waiting period. Whether they could re-assume control and make it stick in court is an open question, but my money would be on, "No."
The only thing I'm aware of that would trump all those court decisions is a Labor / Management contract, very much parallel to what the NFLPA has with the NFL owners. The college players would be members of the union, the college presidents would act as owners, and they would negotiate mutually-acceptable answers to all these questions.
Which is what I think is coming. Not because I think it's the best solution, but because I think it's the only way to impose legally-enforceable structure on a situation that is currently wholly unstructured. As
@crimsonaudio has pointed out, the devil's in the details, and the specifics of such a solution would dictate how I feel about it.
Note: It's possible that federal legislation could impose some structure. But Congress has shown no interest in doing that, and anything they did pass would be tied up for years in court challenges. Which is why I think the union / management path is the more likely solution.
And it all comes back to the NCAA and presidents having their collective heads in the sand (or some other dark, damp and smelly place) and not addressing a situation that clearly would not stand up in court. So the courts did it for them, and imposed their own solution -- which is essentially every man for himself.