Your second last para makes no sense. If pro teams don't care about BY, then why would colleges care about BY if they go pro. They would only care about talent, irrespective of age. ECNL would still sell based on a college route, albeit now a pro route. The issue would be numbers. You would no longer have 300+ D1 "programs" (lmao) plus the rest as the colleges couldn't pay those players imv. Title ix could/would be defunct as colleges could/would just go for pro teams and dump everything else. If the bottom comes out of the numbers, then ECNL has no pathway for the over whelming majority of players so why would anyone pay thousands every year.
As for transfer fees, that's a whole other can of worms. Youth clubs are paid to "develop", if someone then pays for that player, wouldn't they pay the person who paid for the development .. the parents generally. Different system to the rest of the world, and it would defo end up in court of the clubs decided they should get paid twice, lol. Either way why would colleges pay, they would just compete for the 1% of talent they care about by offering more than the other guy. It's not like the clubs decide which colleges the players go to!