Yeah, I think Disney would be perfectly happy paying that sort of fee to keep those IPs locked away. The very last thing they'd want is to let something go, and then some time later discover that someone else has turned it into a valuable product. Not only are they losing out on that profit but now there's a competitor out there. Better to just sit on those IPs forever.

If you instead start jacking the price up year after year until it costs billions to keep an IP copyrighted, why not simply declare it public domain at that point and be done with it? I think a hard cutoff makes a lot more sense. And that way nobody needs to go rummaging around through registries to see if they can use any little thing, they just need to know when it was first published.