This is the speculation of media analysts after the unexpected decision by his eldest son, Lachlan, 33, to quit the News Corporation television and newspaper empire.
For years the business and media world has focused on which of Murdoch's children would take over. Murdoch himself has said he would like a member of his family to succeed him.
Lachlan's resignation, however, leaves just one of Murdoch's four adult children in executive positions, his brother James, 32.
Lachlan resigned ostensibly to return to Australia with his homesick ex-model wife, Sarah, and their infant son, Kalan. Yet speculation is rife that the real reason he resigned is frustration at being in a "non-job", third in the pecking order behind Rupert and the well-respected chief operating officer, Peter Chernin.
Observers, who keep watch on the undercurrents in News Corp in the same way Kremlinologists kept a close eye on the Soviet leadership during the Cold War, believe Chernin is now the likeliest contender for the top job.
Media analysts believe that some sort of deal might have been offered to Chernin to prevent him jumping ship earlier this year to become chief executive of Walt Disney, replacing the veteran Michael Eisner.
"[Lachlan's departure] adds greater credence that Peter Chernin will be the near-term successor to Murdoch," said Richard Greenfield, an analyst at Fulcrum Global Partners in New York.Reuse content