Shiver our timbers - could POTC exist without Johnny Depp?Johnny Depp has cast doubts over his future in the Pirates of the Caribbean franchise.

With the fourth instalment due to hit cinemas this month, Depp appears reluctant to commit to a fifth outing as Captain Jack Sparrow.

The sequel to Pirates of the Caribbean: On Stranger Tides has already been submitted by scriptwriter Terry Rossio and producer Jerry Bruckheimer is on board, according to The Hollywood Reporter, but Depp is holding back.

"Boils down to story, script and filmmaker," he told the magazine.Depp in POTC - On Stranger Tides

"It's not something where I would say, 'Let's shoot it next month to get it out by Christmas 2012," he added.

"We should hold off for a bit. They should be special, just like they are special to me."

He appears to be speaking from experience - Depp faced back-to-back filming for Pirates of the Caribbean: Dead Man's Chest (2006) and Pirates of the Caribbean: At World's End (2007).

The 47-year-old’s hesitation to rush aboard the next flick could also stem from the "monstrous" back pain he said he suffered on the Stranger Tides set when a stunt went wrong.

Bet Disney hopes Depp is having a heart moan rather than walking the plank on its most lucrative film series.

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