[frobozz]

"A significant decline", not a total collapse. Prior to IP laws, individuals took matters into their own hands to prevent losses due to plagiarism. I wouldn't be surprised if the removal of legal protection would lead to more ubiquitous and intrusive DRM.

That said, one potential advantage is that if content is being produced simply because creation is human nature, rather than because a similar item sold well last year; it could lead to higher quality output.