One enterprising research, but certainly interesting, would be the quantification of identifiable prior-created, unpaid matter in major commercial works. Any doctoral thesis on the matter would be a certain hit. Fantasia and Paul Dukas plus Moussorgsky; all the Grimm's and Perrault's stories for other Disney Creations. Applying the same principles (or ends) supporting Eldred, wouldn't that be a big time theft?
Parodying Brecht, what are small time infringers, compared to a large commercial copyright holder?