LOS ANGELES — TV viewers hooked on cliffhanger episodes of hit shows such as "Heroes" and "Grey's Anatomy" could be left dangling if writers walk off the job.

With Hollywood writers poised to log off their laptops as soon as Thursday, TV networks were bracing for the need to fill the airwaves with reality shows, game shows and even reruns if a threatened strike devours their script inventory.

Viewers could start seeing an onslaught of unscripted entertainment by early next year, when popular series such as "Desperate Housewives" and "Heroes" run out of new episodes.

"I was in a network meeting today, and they were referring to the fact the timing is really good for reality producers," producer Mark Cronin said.

He and partner Cris Abrego have been consistently busy with shows such as "Flavor of Love," "I Love New York" and "The Surreal Life."

But "it's going from 50 mph to 70 mph," Cronin said, adding that networks must "protect themselves and fill their airspace."

Members of the Writers Guild of America and the group representing film and TV producers are set to meet today with a federal mediator after scant progress in contentious talks that have dragged on since July.

With the current contract set to expire at midnight Wednesday, negotiators remain far apart on the central issue of raising payment for profits on DVDs and shows offered digitally on the Internet, cell phones and other devices.

More than 5,000 members of the Writers Guild of America recently voted, with 90 percent authorizing negotiators to call the first strike since 1988 if necessary.

The Alliance of Motion Picture and Television Producers, the group that negotiates on behalf of networks and studios, has said networks will continue to air quality programming.

"CBS is not going to go blank," CBS Corp. President and CEO Leslie Moonves has said.

A newcomer to TV's writing ranks earns about $70,000 per season for full-time work on a show.

Veteran writers who move up to a story-editor position would get at least a low six-figure salary, with a "written by" credit on an hourlong script paying an additional $30,000 plus residuals.

Writers are free to negotiate for higher pay, and people who produce or co-produce — called "hyphenates" in industry parlance — earn more.

If writers walk out, the effect wouldn't be felt immediately. Networks have enough episodes of shows such as "Ugly Betty" and "CSI" written and in production to last at least through the end of the year and possibly into next February, industry executives and analysts said.

But after that, schedules will run into trouble.

Producers already have tried to hurry shooting in preparation for a strike but not always successfully.

The CBS sitcom "How I Met Your Mother" was asked by 20th Century Fox Television to shoot an extra episode during a planned production break last week.

"It simply would have been impossible, so we said no. That was pretty much where it started and ended," said Jamie Rhonheimer, a writer-producer on the series.Film production would not immediately suffer the effects of even a prolonged strike because of the long lead time required to make features.

Still, studios could soon be wrestling with plots and endings for unfinished 2009 blockbusters such as "X-Men Origins: Wolverine" and the next James Bond flick.