It looks like this will be the norm in a couple of years. I expect that there will be a time when no music or books are entering the public domain anymore.

Well you know, if the author's grand-grandchildren don't live off his work, it might make him not want to create anymore...

Or it could be just that the corporations which bought many of the money-making copyrights long ago want to continue to receive royalties from it indefinitely.

A tangential question - if ownership is established, would said owner have a case against Warner for the $2M a year they've been raking in against an illegitimate copyright claim?

The timing basis for copyright starts counting down at the date of first authorized publication, not at the state of conception. Well, pre-1976; the 1976 copyright act actually starts the clock from the date of fixation.

The essential problem with the Happy Birthday song is that no one is quite sure who created it, and thus no one is quite sure which publication (if any!) would be an actual authorized publication. It thus falls under really, really gray areas of the law.

It should be noted, however, that the most plausible scenario that could win a victory at court (in terms of being able to prove that copyright exists) would have the copyright expire in about 400 days anyways.