It reminds one of the demise of the great magazines of forty years ago-Life, Look, Saturday Evening Post, and others. They failed because their audience fragmented. Advertisers began to target specific readers of specialty magazines. Women's magazines have survived this fragmentation because they, like television, provide trash, albeit elegantly designed trash. They, like network television, prosper on shallow writing and sex.
Public broadcasting is the shining exception to the fall of television.
Since the Sixties it has built its audience slowly, staying generally with quality, sometimes being dreadfully boring, more often fascinating. C-SPAN also has grown slowly over the years, expanding its quality programming. Again, C-SPAN is sometimes boring, more often great.