(Newser) – There's going to be an empty throne in the Magic Kingdom two years from now—and it's suddenly far from clear who will fill it. Walt Disney COO Tom Staggs, widely seen as the heir apparent to CEO Bob Iger, unexpectedly announced his resignation on Monday. Sources tell the Wall Street Journal that the 55-year-old Staggs, who had been rising through the Disney ranks since 1990, quit after learning that the board had broadened its search for Iger's successor, suggesting he was unlikely to get the job when the CEO retires in June 2018.

Insiders say that Disney, which faces major technological challenges in the years ahead, may now look outside the company for a CEO for the first time since the 1980s. One name in the frame is Facebook COO Sheryl Sandberg, per Reuters. Other possible candidates include 21st Century Fox Executive Vice Chairman Chase Carey and CBS chief Leslie Moonves, Variety reports. There's also a chance that Disney could choose another internal candidate—or that Iger, who will be 67 in 2018, could be persuaded to stay on for a few years. "Internally this sets up a horse race, but I'm not sure who the horses are," says media analyst Tom Vogel. (Read more Disney stories.)

