To my limited understanding, the Supreme Court has been very clear that the workers' rights can only be abridged (say, by a salary cap) if they approve an agent authorized on their behalf to negotiate those rights away—i.e., a players' union.

It's the same legal environment that's led every major league pro sport to end up with that solution.

Which is why I've long felt it was the exact opposite of visionary when Northwestern and Spanky Fitzgerald crushed the union movement among their players. They could have gotten out in front of it and looked like champions of their players' welfare, just by going along with what they ultimately couldn't prevent anyway. But just like the NCAA as a whole, they had to greedily try to keep the whole loaf.