I think it's done this way as a compromise to the current copyright holders. Disney can and will easily pay 100,000 per year for all their productions in the v

I think it's done this way as a compromise to the current copyright holders. Disney can and will easily pay 100,000 per year for all their productions in the vault, so no change in the status quo there. However, most sci-fi books from the 70s which are already out of print, will become public domain, and you can now write "fan-fiction" for it and get paid without having to seek out the original copyright holders (if they still even exist). It's questionable if Asimov's estate will pay 100,000 per year for each of his short stories, and lots of those make fantastic premises. If we didn't have eternal copyright, they'd make up a part of our literary landscape like Romeo and Juliet, or fairy tales do---something that can be freely alluded to, or redone.