PASADENA, California (Hollywood Reporter) -- Fox's veteran comedy "Malcolm in the Middle" will end its seven-season run May 14, while "That '70s Show," now in its eighth season, will bow out four days later, the network said Tuesday.

For the homestretch, "Malcolm" will return to Sundays beginning January 29, opening the night at 7 p.m., a slot generally occupied by cartoon reruns.

Meanwhile, Fox is in conversations with former "That '70s Show" stars Ashton Kutcher and Topher Grace to return for the show's finale, Fox entertainment president Peter Liguori said during the network's portion of the Television Critics Assn. winter press tour.

While the end for "Malcolm" and "That '70s Show" comes after long, successful runs, the untimely exit of the network's Emmy-winning but low-rated comedy "Arrested Development" after three seasons -- two of them abbreviated -- brought up a lot of questions.

Although the network touts airing the two-hour block of the final four episodes of "Arrested's" current order on February 10 as "season finale," Liguori stressed that a future return of the show to Fox is "highly unlikely."

"Arrested's" producers, Imagine TV and 20th Century Fox TV, are fielding offers from two networks, Showtime and ABC, which are interested in picking up the acclaimed series.

With no strong new comedy additions in the past couple of seasons ready to fill the void left by the departing comedies, the network's brass are putting a lot of muscle behind the rollout of its midseason comedies "Free Ride" and "The Loop," using the network's best launching pad, the blockbuster "American idol," to help their chances.

The partially improv "Free Ride" is slated for a March 1 preview, following a special 90-minute episode of "Idol," and "Loop" is getting a preview March 15, leading out of an "Idol" results show. On March 12, "Free Ride" moves into its regular Sunday 9:30 p.m. slot, temporarily replacing "American Dad," while "Loop" will relocate to its regular Thursday 8:30 p.m. period March 16.

Fox also is taking another look at two comedies that have been off the schedule for a while.

"King of the Hill," which is not in production but has never been officially canceled, might come back as early as January 2007 if discussions with the series' producers are successful, Liguori said.

Meanwhile, there haven't been any active negotiations to revive "Futurama," which, much like "Family Guy" before it, is enjoying a second life on Cartoon Network's "Adult Swim" late-night block. But Fox executives are keeping a close eye on the series' newfound success.