Black Gold

When are they finally going to release Jimi’s album Black Gold which he recorded shortly before he died? Most of Jimi’s original fans are either old or dead, so why are they still only gradually releasing his unreleased material; we only get a new album of substance about once every 3 years? I don’t know why artists such as The Beatles, Beach Boys, and those who own the rights to Jimi Hendrix’s music seem to act as if they are waiting for some big anniversary or reemergence in popularity to release the remainder of their unreleased material. For example, if the unreleased songs of the Beatles weren’t included on the 50th anniversary editions of their respective albums, when do they expect to be a more appropriate time to release them?