The long-running, five-movie series—which has grossed more than $4.5 billion worldwide, according to Box Office Mojo—is struggling to come up with a new installment, according to a report in Deadline. Screenwriters Rhett Reese and Paul Wernick, who co-wrote the hit Deadpool films, were reportedly working on a Pirates entry that would relaunch the saga without Johnny Depp’s swashbuckling Jack Sparrow character.

But Deadline says the duo has left the project, and that there are signs the Pirates big-screen universe might be exhausted. If so, it would mean the end of one of the most successful film series of the 21st century—one that started in earnest as a theme-park ride at Walt Disney’s amusement parks, and wound up becoming an Oscar-nominated box-office plunderer.

The series began with 2003’s risky Pirates of the Caribbean: The Curse of the Black Pearl, which introduced audiences to Depp’s grizzled, Keith Richards-inspired Sparrow character, and became a surprise smash, earning more than $300 million in the U.S. (and landing Depp an Academy Award nomination for Best Actor). By the time of 2017’s Pirates of the Caribbean: Dead Men Tell No Tales, the series was losing its sea-legs at the box office. There were also reports of a troubled production, including an incident in which Depp—who’s been plagued with financial and legal troubles in recent years—injured his hand, resulting in filming being shut down for about two weeks.

If Disney does shut down Pirates, it can take comfort in the number of currently thriving franchises it oversees, including the Star Wars and Marvel films, as well as forthcoming sequels to such animated hits as Frozen and Toy Story. And it hasn’t given up on expanding its theme-park properties just yet: In 2020, Dwayne Johnson and Emily Blunt will star in Jungle Cruise, based on the long-running ride.