IMO, the bigger issue is all the things copyright covers. I don't think there's a particularly damning public interest in being able to publish an author's book without paying them. For art preservation reasons, the copyright limit shouldn't be indefinite, but IMO as long as somebody's around to claim ownership, and offer a legitimate means of obtaining access to a work of art, it's not a big deal for them to have a monopoly on such.

But copyright covers a lot more than just the right to produce copies of a specific work. The monopoly on derivative works serves the public significantly less. IMO, this one should taper off pretty rapidly. Maybe 20 years as is, then another 20 where you lose the ability decide who can or can't use your work, but they still owe you royalties.

Then there's the clusterfuck that is software. With how rapidly the world around software changes, its protections should be substantially shorter. For derivative works of source code, I'd pitch skipping the complete monopoly step entirely. You get a decade or two where people using your software owe you royalties unless you say otherwise, then nothing.