Where does it stop?
Well, it seems there are two reasons for somebody to pay the players. One is that somebody thinks an athlete endorsing something for $X is going to increase sales of said product by some number that is higher than X. I have not seen that happen. The other is the same reason boosters paid players illegally for decades. Rich old men who are willing to dip into their pockets because they want “us” the beat “them”. My money is on people with money. There is a hell of a lot more money in Texas, south Florida, and southern California than in places like Alabama, Oklahoma, or Ohio. In 10 years, the top teams are probably some mix of Texas, A&M, Miami, USC, and just a few more. As to MU, well, our president is, AFAIK, the richest college president in the country, our governor is an alumni and in the Forbes 500, and the early leader for next governor is also one of us and owns 20 car lots.
As to the “transfer portal”, it is a stupid idea. Eventually the schools will figure out that they have to tie the pay to staying put. AKA a contract. Welcome to minor league pro football.