Originally Posted by pinniped
The airlines know mileage-runners and segment-runners exist. If they decide to put an end to the game, they can do so immediately. Minimum-stay requirements, maximum-segment limits. Some of these are already in place on certain routes/fares. (For example, there is a limit to how wacky a routing AA.com or United.com will book, isn't there?)
Here's a question, with the alliances--such as SkyTeam, the one with which I am most familiar--it is possible to circumvent minimum stay rules and accrue the necessary mileage and EQM or points. It's easy to nest tickets such that you don't have to satisfy a Saturday night stay. I am sure they could try to end this activity too; however, I don't know when anti-trust issues kick in. Taking advantage of codeshares of alliances might be harder for airlines to police.