Problem is that all the major networks have niche channels that cannot make it on their own and are subsidized by the channels that do make money. So a LGBT channel or a channel about fitness is paid for by being packaged with a channel like Discovery or ESPN. This is why companies like Time Warner, Viacom, ABC/Disney are opposed to ala carte programing, it would cause them to lose tens or hundreds of millions per year.
“channels that cannot make it on their own”
Those channels belong on the internet, which is where all the channels will eventually be.