There's a little wiggle room here...didn't Red Auerbach draft a player who was still a junior and not eligible for the draft? The player never declared, and there was no ability at that time to leave college early. I think there will need to be a rule that states that if a player leaves college, and spends more than one year unenrolled at any college or university anywhere, they lose all eligibility.
The Olympics fell apart to a degree when they started to allow professionals. I realize this isn't quite the same, but how many medals could Mark Spitz have won as he had only one Olympics to make his haul. During his college career he was studying to be a dentist. Had there been dough to prolong a college career with NIL money, possibly he would have robbed together enough income with endorsement to swim in 3-4 games. Michael Phelps gats the credit for being a GOAT as he had many Olympics to increase his stash.
To that end, you could easily have players hang around, sucking up NIL money for years, and never getting out of the way for the younger players. This could kill the goose that laid the golden egg for the WNBA, if players don't hang around at a college for a few years to build up a fan base, there's no transference of that base to the pros. We root for our college team, but never bother watching a pro game.