Science Television: Does Joe Public Care?
People like science, and will watch anything they can grasp. If a channel not only dedicates itself to presenting truly in-depth scientific shows, but also brings them up-to-date on the background science that leads to it and can give people reasons why it is useful science, they will watch.
One of the reasons people keep watching the same kinds of shows they do on the Discovery channel is that the topics are usually that which they have the background on already and so can grasp. I watched Cosmos when it originally aired during my first year of high school, and I had only the barest inkling of the topics he covered, but Sagan presented each episode in a way that helped me get up to speed quickly on what he was talking about before he fed out the hard science. In effect, making it all pretty easy science.
A hard science channel won't succeed if it's not willing to get people up to speed on the topics like that. If you want a channel that just dumps hard data on people's laps that they have no background information on, no, I don't think it will succeed.