Now the man in black’s son, John Carter Cash, told the Guardian that there exists an additional four or five albums worth of material yet unreleased.
"There are a few things that are in the works right now -- probably four or five albums if we wanted to release everything," he said.
Cash also told the Guardian there may be a trove of outtakes from his father’s days recording with production godfather Rick Rubin at American Recordings. Cash and Rubin started working together in the 90s and Cash’s 1994 album American Recordings released on Rubin’s label of the same name is credited with launching Cash’s comeback. Rubin has released two post-humous albums since.
"There may be three or four albums' worth of American Recordings stuff, but some of it may never see the light of day,” Cash’s son told the Guardian.
Though Rubin, also speaking to the Guardian, said, “We released the work we had been planning to release along with John [Carter Cash] and the idea of the Unearthed box set of outtakes was his idea. We will probably put out additional Unearthed material recorded since the last Unearthed box, in keeping with John's wishes."
Either way, it looks like the legend will join J.D. Salinger and Tupac Shakur in continuing to release material long after his death.