If anyone thinks that this NIL system is going to make bagmen and the like obsolete, they're just wrong. There are underground markets for virtually every legal product and service. For example, you can still buy illegal pot from street dealers in states where it's totally legal. And bootlegging cigarettes from low-tax states into high tax states is a major criminal enterprise.
So, star players who will now have to go through the hassle of paying taxes on their NIL income will be delighted to discover that they'll still be getting the traditional $100-$1,000 post-game handshakes from alums and perhaps bigger "under the table" and "tax-free" cash payments from unscrupulous boosters as well. Will there be less of that kind of monkey business than before because of the NIL? Probably. But I can assure you that the bagman is not going to go the way of the dinosaur.