A new Reuters piece on Keith Richards revealed that he will return in Pirates of the Caribbean: On Stranger Tides. Here's an excerpt from that article:

"Johnny Depp, who played the lead role in the 1990 movie Edward Scissorhands credits Keith Richards for inspiring his character Captain Jack Sparrow in the Pirates of the Caribbean films, and the two are currently shooting the series' fourth installment, where Richards reprises his role as Sparrow's father."

Keith Richards first appeared as Sparrow's father, Teague Sparrow, in Pirates of the Caribbean: At World's End and this new report is the first indication that he is reprising his role in the fourth movie.

We'll be sure to keep you posted with any further information on Pirates of the Caribbean: On Stranger Tides as soon as we have more information.