IP continually used and refreshed can potentially have infinite shelf life. Look at James Bond, the original books came out a long time ago. Look at Lord of the

IP continually used and refreshed can potentially have infinite shelf life. Look at James Bond, the original books came out a long time ago. Look at Lord of the Rings, those books came out a long time ago. There's a reason Disney keeps fighting to extend copyright, despite how much of their own material is derived from works based on expired copyright.