A central registry of extended copyrights is not impossible; there's plenty of institutional inertia in government offices to assure continuity (USPTO has been

A central registry of extended copyrights is not impossible; there's plenty of institutional inertia in government offices to assure continuity (USPTO has been around since 1871, Library of Congress since 1800), and the extension fees could easily pay for a database of works. Heck, we already do that with registered copyright. It won't even be a large corpus; the works that anyone would care about after 30 years (or, in better concert with the current system, 70 years) would be rather manageable. To eliminate "grey area", make the USPTO (or LoC or whatever) the final word on whether something is still registered. Ask 'em, they say "yes" or "no", and you're done. Instruct the registry to provide wide latitude in considering slightly different versions the same work to cut down on combinatorics. It actually puts more of a book-keeping burden on the copyright owners than the government, but if you have 30 year+ still-producing assets, presumably you can manage such a slow-motion system. It's not a perfect system, granted, but it's better than the alternative: eternal or eternally-extending copyright, with the original horizon being "Steamboat Willie". With a registered-renewal system, Disney can keep their crap and we can get the rest of the corpus. (For bonus points, the registration fee increases with each renewal, to make sure you really think it's valuable. Powers of two would be nice.)