Good news (for cable), bad news (for broadcast)

How much damage can cable do to the networks? Consider: This is a breakout summer for cable, the season that cable channels bring out their big guns while the broadcast networks lie dormant with reruns and reality detritus.

So far this summer, cable shows have been giving their channels record ratings, while the broadcast networks continue to slide.

Amongst the success stories: “The Closer,” now in its third season, and newcomer “Saving Grace” on TNT; “Damages” on FX; “Army Wives” on Lifetime; “Burn Notice” on USA; and “Mad Men” on AMC (granted, “Mad Men” – tonight at 10! – isn’t what you’d call a huge hit, but it has doubled AMC’s Thursday night ratings).

“We’re at the tipping point,” Steve Koonin, president of Turner Entertainment, told the New York Times. “It’s our belief that we and the other basic cable networks can begin matching the broadcast networks series for series. It’s only a matter of time before we have as many big hits as they do.”

The broadcast networks may still inspire viewer loyalty amongst older viewers, but to younger viewers, they’re just another stop along the dial while channel surfing. And nothing suggests they’re going to be able to reverse that trend as the three-network universe recedes ever further into history:

* CBS has shed 9% of its viewership from just last summer, 14% in the target demographic of viewers aged 18-49 and 21% in younger viewers.

* NBC has lost about 11% in total viewers, demo viewers and younger viewers from last summer.

* ABC, too, has lost 10% in total viewers, but 16% in demo viewers since this time last year.

* Fox has held relatively steady, while The CW is hard to gauge because at this time last year it was both The WB and UPN (but suffice it to say that The CW isn’t exactly on fire).

Keep in mind – these are losses from just a year ago, not the accumulated trickle of years of audience erosion. This means fewer and fewer viewers are seeing all those promos for the broadcast networks’ new upcoming fall series. And every year there’s a chunk of viewers who, finding they like what they see on cable, don’t have the compunction to migrate back to broadcast come the fall.

So look at broadcast’s hemorrhaging this summer alongside cable’s continued growth, and again, we’ll ask: How much damage can cable do to the networks?