Disney's (NYSE:DIS) Lost -- produced by its Touchstone Television and aired on its ABC network -- may be a hit, but the show's viewership, like its cast of secretive survivors, has been steadily dwindling. Now ABC and the show's producers have announced that Lost will run for three more 16-episode seasons, ending in 2010.

That decision implies that the show won't attempt to artificially extend its story's life beyond the creators' original intentions. We've all experienced TV shows that increasingly lost the plot over time, until they were banished to the deserted island of cancellation. To date, Lost's success has been a rare bright spot in an industry increasingly struggling to keep fickle viewers amid a blizzard of competing draws on viewers' attention.

Of course, some argue Lost has already exhibited ominous signs of the potential for "jumping the shark." (Curiously, ABC is the network responsible for coining that phrase, based on the notorious Happy Days episode in which the Fonz did exactly that, on waterskis.) Many Lost viewers felt cheated when last season ended on an unsatisfying string of episodes. This season, fans have had more new episodes in a row, but the plot has gotten increasingly convoluted. I doubt I was alone in my frustration over the six-episode run that opened the season, in which it often seemed that the writers were piling on more questions without giving any much-needed answers. (And who could forget the parade of supporting characters who've been hastily introduced, then just as hastily offed?)

A definite ending -- and end date -- are great news for Lost, lessening the risk of subjecting viewers to multitudes of plot twists that might never be resolved. Indeed, news articles say the show's producers asked for a "finish line" so they could time resolution of some of the plotlines. I'm glad to see that they get it.

Then again, given the ratings decrease this season, ABC and the producers of the show still have plenty to worry about when it comes to execution if they want to keep Lost going for the next three years. Don't let us down, guys. I need to know what happens.

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Alyce Lomax does not own shares of any of the companies mentioned. She watches Lost and has a vast repository of theories about the island's mysteries. The Fool's disclosure policy is 100% polar-bear-free.