IP should not expire as long as the intellectual product is not publicised, i.e. while it is in the head of whom produced it. But if it is publicised, i.e. published, it is public, and no longer property. If I had a house, that's physical property. If I and my family live in it, it's our property. If I let the public in, i.e. publicised it, then it is public, and essentially not property anymore.