Well, yea, no one can stop someone from paying TJ Watt $10 million to appear at a birthday party or paying a college player $500K to do nothing. They get that money. But it would count towards the cap. As a fan of the team, I would be considered a "representative" who cannot pay Watt's salary outside of the cap. However, stronger language would be put in next time around.
Collectives for sure will be gone because those are plainly obvious "team representatives." The only possible way around it is to have individual donors pay appearance fees like in your TJ Watt example. But even then, there would very likely be some third party who judges what fair market value is for someone like him to show up at a kids party. Probably something like $25K. So the other $9,975,000 he was paid has to count against the cap.