Considering that most channels seem to work under the model of "Get as much to fill the schedule for as little as possible" I'm not sure that very much of value will be lost.
Look at it another way: The Travel Channel hires many different producers for it's shows. If the travel channel goes away, the channels that survive will be eager to snatch up the shows from the Travel Channel people (hypothetically) actually watched while all the filler just dries up. So now you have channels competing with each other to get people to buy their channels (like HBO does now), rather then just hoping people land on their channels for an hour and see a few commercials before moving on.
I have a feeling that channels will probably stick better to their formats, too. If they drift away from what their core wants, they will have to try and re-market themselves for their new format while the original watchers maybe don't renew that channel the next time their contract comes around.