I could have sworn I read an article last week saying that they were going to do this, but scrapped the idea at the last minute. I think it was either aviation weekly or msnbc.com travel section.
The article sounds like it is talking about the advance purchase (i.e. lowest) fares. It sounds like United is trying to force the business traveler to use full fares.
While raising the fares is actually a good idea, forcing a minimum stay is not.
Modern revenue management systems like United uses don’t have hard and fast “fare rules” with minimum stay requirements like that.
It will always be possible to get a low fare on a route that has a lot of competition and you’re booking on a date that happens to have open capacity (not all too common these days).
Airlines are constantly monitoring what other airlines are charging for the same itineraries. They aren’t going to charge a significantly higher fare unless they are virtually sold out.
They also realize that you could just go on an Online Travel Agent and book 2 one-way tickets. They will never make a roundtrip cost more than the equivalent 2 one-ways as then they’d lose share on their preferred distribution channel.