These are numbers from the estimable website TV By The Numbers (refs. below).

Bill Gorman shows two things:

1) the decline of broadcast networks (yellow column to the left)

2) the rise of cable networks (yellow column to the right) 

As Gorman notes today, cable is not just growing but moving to the center.  In the case of Bravo, for instance, this means moving from indie film, drama and the performing arts to reality, fashion and celebrity.  TLC was once a "place for learning minds" and now gives us Jon & Kate Plus 8.  The cable alternative now has a carnie instinct for a cruder entertainment. 

The question is this: does this movement to more popular themes represent a compression of cutural offerings and a dumbing down of programming.  We can argue this a number of ways.  But I am impressed with the fact that reality television is often a very successful ways of getting something like the lives of real(ish) Americans into the programming mix.  Without the innovations driven by cable, there is no way we would now have such detailed ethnographic treatments of, say, the Housewives of New Jersey and Orange County

It's a question then of winners and losers.

Two groups are relatively displaced by the "new cable:" the avant garde who prefer indie content, and taste elites who care about arts content. 

Two groups are served: a carnie audience interested in sensational coverage and the rest of us who like this window on other worlds. 

References

Gorman, Bill.  2008.  Updated: Where Did The Primetime Broadcast Audience Go?  TVbythenumbers.com.  December 03, 2008.  here.  (source of the image above)

Gorman, Bill.  2009. As Cable Networks Abandon Their Roots to Grab Audience, Where Do The Niches Go.  TVbythenumbers.com. here.