(CNN) -- This season has been very good to NBC.
ABC, CBS and Fox — not so much.
This year's television season is only a few weeks old, but there are already signs about how it's shaping up in the ratings.
The news is not good.
For the first three weeks of the 2012-2013 season, according to Ad Age, ABC, CBS and Fox are all down by double-digits in the key 18-49 demo, which helps sell advertising
Only NBC is up.
(Fortunes for The CW, the netlet co-owned by Warner Bros. and CBS, are still unclear.)
Is network TV dying?
According to Robert Thompson, director of The Bleier Center for Television and Popular Culture at Syracuse University, it's not that simple.
"Network TV is certainly not where it was back in the years of the 'Milton Berle Show,'" he said. But he added that the major networks still have the most money, and can grab the most eyeballs, even if viewers have scrambled their viewing habits.
It's not that no one is watching TV — it's just that they're watching it across many different platforms, like laptops and tablets or through streaming services like Hulu.
In this "multichannel universe, narrow-casting is the order of the day," Thompson said.
With so many options, people tend to seek out what's tailored to their tastes, which helps explain the explosion of cable channels since the 1980s.
In 2009, they accounted for more than 40 percent of household viewing, according to Nielsen, while networks made up 25 percent.
"The Walking Dead" is one of TV's biggest shows, dominating its time slot and the cultural conversation — and it's on AMC.
By comparison, Thompson said, part of the networks' problem has been a lack of "big new things:" the shows that can pull people back to their couches.
In 2011, it was "The Voice" on NBC; in 2009, it was ABC's "Modern Family."
"It's not that this year they said no to the next 'Modern Family' and chose the wrong thing," Thompson said. "It may be that the next 'Modern Family' didn't present itself."
Of the 20 new shows launched by the five major networks this year, only one of them — "Revolution" on NBC — has been an overachiever, by debuting big and staying that way.
Season-to-date, its 18-49 rating is almost twice NBC's average, according to TVByTheNumbers.com.
It may be no coincidence that this year's success stories are genre shows, like the post-apocalyptic "Revolution" and the post-apocalyptic "Walking Dead," or even The CW's "Arrow," about a brooding, hooded superhero.
The success of "The Voice," meanwhile, means viewers remain open to big, splashy reality and competition shows, Thompson said, even if NBC risks overexposing the show.
The networks still have the benefit of a lot of marketing and production muscle: their shows can be bigger and their ads can be louder.
Some of the buzziest programming however, including ABC's nuclear sub thriller "Last Resort" and its country music soap "Nashville," is also some of the lowest-rated.
Thompson suggested that prestige programming is now better left to cable and the smaller, more passionate audiences who flock there.
Sitcoms are still bustling, even if several high-profile fall launches (Fox's freshman "The Mindy Project," ABC's pairing of returning comedies "Happy Endings" and "Don't Trust the B---- in Apartment 23") haven't broken through.
It doesn't matter, Thompson said: comedy properties are full of potential — not just in primetime, but in syndication, where they can be replayed at hefty prices for years.
Ad Age's annual survey of TV commercial prices, released at the end of October and based on pre-season estimates, backs up Thompson's claim: seven of the 10 costliest shows are comedies, including "Modern Family," Fox's "New Girl" and CBS' "The Big Bang Theory."
"The first three things on my Top 10 list of things to do would be develop half-hour comedies, develop half-hour comedies, develop half-hour comedies," Thompson said.
Meanwhile, the networks are in a "holding pattern," waiting for the next big thing to stop the slide, he said.
The trick is finding them.
"The content is everything," Thompson said. "In the end whether people are going to watch hits on their laptops or five days later on their DVRs or watch it the old way, if you get a big hit like a 'Survivor' or a 'CSI' when it was at its peak, then you're going to be fine."