There's no apparatus to enforce rules. It's as with all things in culture/society. They get more and more "liberal" until things reach a breaking point. They're are ruined forever or a hard reset occurs.
With the new 12 team playoff and 2 mega conferences, we will see new levels and forms of corruption and bias.
A hypothetical 1-loss Miami team will get snubbed for a 2-loss SEC team to get that 12th spot in the CFP.
Teams will get more brazen with tampering. I can realistically see teams paying a player at their current school under the table to transfer after the season is over. Building a sort of farm team.
Even if there a measures enacted to control the portal, the enforcement will be lacking by design.
Pre-portal, the bluebloods were paying players or their families. We've reached a higher level of parity now, but when caps and transfer limitations come into play, it gives the bluebloods the advantage again, because they can skirt the rules and not get in trouble.
We're definitely in for a wild ride and I don't think things will ever really "improve."