Today, during a rather excellent podcast on DLC, Harmonix representatives spoke at length about the Beatles game, sharing some interesting insights in the production process at Abbey Road. They also spoke about the possibility of future DLC. They said that working with the Beatles could be 'glacially paced'.
"We know that you want more Beatles DLC. We want more to. We're going to continue passing that info from the forums to the music ops team."
While this isn't the same as saying "remaining albums, available tomorrow" (which is what we all want), it is enough to confirm that Harmonix are still interested in The Beatles brand and that, with a little luck, we could be buying new songs some time in the future.