It appears obvious that the most critical aspect is one of a true/enforced salary cap, as the NFL has. This is the reason why smaller market teams in the NFL can win, and consistently at that. Unlike the NBA that has a soft/luxury cap, etc. or MLB that hasn't any cap at all, and, therefore, why it's typically the large market teams having the most success.
NIL in the college game still is problematic in my opinion. I can see where the rich getting richer still exists as those schools that have many and more wealthy boosters still finding a way to get the 5 stars, highest rated transfers and the like extra dough. I can see where the cash bags will still be a tactic to lure better/top players even if that school has maxed out its cap, finding a way "creatively" in avoiding the extra moneys being traced back (W2, 1099, etc.) to the beneficiaries.
Now, if these top/higher regarded players are striking legit NIL deals where they are actually pitching products, services, etc., as the professionals do in the NFL,NBA, etc., well then that's is a horse of a different color as it's truly NIL, their market value, etc. based on same.