In that case, I would do nothing. As suchmoon says, the real owner might try to move the coins at any point between now and decades in to the future. You cannot assume the coins are lost just because that paper wallet goes unclaimed.
Didn't really think about that.. might be a cool souvenir and a cool story to tell my grandkids ... of the day I found something that sparked an educational sojourn down a rabbit hole I've not been down before,... to be rediscovered in my old age......
... or do I tell them a different story?