So is the code I wrote 5 years ago and I don't have the right to rent seek the whole world for next 70 years with it.
Let me reiterate, VAST, VAST majority of all cultural works aren't owned by authors themselves, but their publishers which don't pass on most of the rent they collect. Huge piece of this is owned by rent-seeking megacorporations collecting rent for things they did not create and which royalty agreements have passed long since.
Make copyright 20 years - most profits from content are made in first 5 years. 15 extra on top to be fair. After that, the artists will just actually have to create something new to earn money - just like everyone else in the world.