I think you are talking to a very narrow sliver of players. Plus, the player would need to want to go play NCAA which means going to classes etc for no real reason. If their goal is to play NHL hockey and they are blue chip prospects, I cannot see why that player would want to switch to an environment where they play half the number of games and need to take a full course load. It doesn’t make much sense to me.
The real issue relates to AHL eligibility. If they are drafted out of the NCAA, they are eligible to play AHL early. I think the rule for players being placed in the AHL early will change soon. There probably would be some restrictions like where they are drafted etc. But, that still only affects a small number of players. Most are not physically mature enough to play AHL hockey early. If they are physically mature enough, then chances ar pretty good they are physically mature enough to play NHL. Cowan, as the example, is not physically mature enough to play AHL hockey. Same with Luchanko. Ritchie may be the one that would play AHL. I don’t think there is anyone else.