Cost should rise proportionally to length of copyright to disincentivize retaining copyrights indefinitely.
Ex.
First 10 years - free
Second 10 years - $1k/year
Third 10 years - $10k/year
Fourth 10 years - $100k/year
and so on...
Ex.
First 10 years - free
Second 10 years - $1k/year
Third 10 years - $10k/year
Fourth 10 years - $100k/year
and so on...
I'd like to try exactly the opposite: when a work has been seen by a million people, it becomes public domain — whether that takes one year or 100 years.
Why? Because when you make a derivative work of Harry Potter or Star Wars you are not thinking that you can hoodwink your audience into believing that yours is the original, rather you're writing for a cultural context that assumes that people know the original. And to me that's exactly the underlying idea behind fair use.
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.
Now that I thought about it. The Monster is the best story of the century and it can't be touched.