It seems like what makes sense is protection for trademarks/brands/characters should be infinite, because it’s clear that there’s harm in just letting anybody make their own “Nike” shoes or make a really crappy movie starring “Mickey Mouse”.

But, you could still put actual works in the public domain after ~20 years. I think there’s a difference between being able to freely copy and use a video of “Steamboat Willie” and having full use to put Mickey on any shabby product anyone in the world wants to.