Fuck eternal copyright.
Anything thirty years old belongs in the public domain. You should find no restrictions on the discography of Nirvana or any John Candy film. They're ours, now. That's what the money was for.
But you can train generative models on albums published yesterday. Training is transformative use. Now: sharing a song blatantly similar to Taylor Swift's latest hit will end with her owning your house. Which also applies to actual human musicians. Similarity of the end product is all that matters, for infringement - and only if you share it. Copyright is about copying.
Shredding every MP3 on the internet into a gigabyte of math soup is not copying.
A program that makes new songs, in any genre and subject you can describe, is not the same thing as a pile of records. The program can't play the White Album. The pile doesn't have any ska about weather balloons.
The dumbest possible response to all this AI nonsense would be giving more power to known bastards.