I think that sets a bad environment, because who decides what historically important is? How many years does it become "historic"?
A much simpler and better solution is to not extend copyright to 120 years or whatever the hell it is now [1] (Thanks, Disney!). Twenty years or so should be plenty for all artistic works.
I think an exception for historically important content would be useful. At the very least historical archiving should be allowed, even if you aren't allowed to show it until copyright expires.
But that wouldn't really solve this problem. The owner wants to get paid.