How Long Can 'The Simpsons' Run?

"The Simpsons" executive producer James L. Brooks, left, Executive Producer and Creator Matt Groening, center, and Chief Operating Officer of NewsCorp Peter Chernin, pose for photographs with characters Sally, left, Bart, center, and Homer during the "The Simpsons" 350th episode block party in Los Angeles, Monday, April 25, 2005. (AP Photo/Ann Johansson)
When a show reaches an impressive 350 episodes, it's fair to reflect on its mortality. So how long can "The Simpsons," which hits the milestone Sunday, keep going?

"I don't see any end in sight," creator and executive producer Matt Groening told The Associated Press.

Those are reassuring words for the millions of fans who have remained loyal to the Simpson family through 16 seasons, and counting. Writers are already at work on episodes for 2005-06, the 17th season.

The key to its longevity is simple, Groening said: "We try to keep surprising the audience. That's what you're looking for in television — surprise."

As long as the show can meet that burden, "we'll keep going."

Executive producer Al Jean, who has been with the animated comedy since it was spun off Tracey Ullman's variety show in 1989, muses about other aspects of the equation.

With the ensemble cast signed through the next three seasons, "I would consider it highly likely we will do those seasons," Jean said. He added that he hopes they find the work rewarding enough to continue.

The series features the voices of Dan Castellaneta and Julie Kavner as parents Homer and Marge Simpson; Nancy Cartwright as son Bart, and Yeardley Smith as daughter Lisa.

Castellaneta and Kavner also voice a number of different characters, as do cast members including Harry Shearer (Mr. Burns and Ned Flanders among them) and Hank Azaria (police Chief Wiggum, Moe and others).

The future also depends on the continued profitability of the brand that has brought an estimated $1 billion-plus to Fox and parent company News Corp. through the TV show, DVDs and a vast array of other goods.

Although ratings are not stellar compared to top shows like Fox's own "American Idol," "The Simpsons" has held steady with just under 10 million weekly viewers for several years and remains Fox's Sunday bulwark.

It's a creative mainstay as well, say Groening and Jean.