If I wrote a book about Bean Man the super hero, than I should maintain all rights to the concept of Bean Man and the related “characters/world” until I die or put it under public domain. The rights can be inherited by 1 generation, but they have 10 years to do something relevant with it or it falls into public domain. Also if the IP sits unused for 20 years, clear derivatives can be made so long as it’s clear the original creator was not involved.

However, the actual product, the books I write fall into a different category. After 30 years or, 1 year unavailable to legally purchase by an average person*, the books become free to share under a creative common license that does not allow for derivatives, or profit. In other words, the book it self becomes free for everyone but someone can’t take the IP and make a new “Bean Man” story (unless the copyright is no longer in effect).

* if I try some shit like sell it cash only on the 31st of February or charge a absurd price, all of my past and future works will be put into public domain as a “fuck you for being piece of shit”.