What if you clean up the basement of your dead great grandpa and you find a big fat chest full to the brim with gold and you sell it for say 100 million and you are obliged to register that sale with financial authorities and then, yes then, they tell you that the gold was acquired by your great grandpa 110 years ago and there is a law stating that when something is lying around dormant for >109 years, it automatically belongs to the public and must be returned to public treasury, what then? Honest question, what would you think?
I think there is already something like this. It is called the Copyright Act, and its relative Copyright Term Extension Act.