I feel like there needs to be at least 2 separate sets of rules for copyright.

For independent artists, I think it's pretty reasonable that copyright should last for their lifetime and maybe a little longer to make sure that their spouse, children, or other dependants can be cared for before the work goes public domain. We can quibble over exactly how long after death that should be, but that seems pretty fair to me (personally I'm tempted to say 18 years+9 months, so if hypothetically a male artist knocked up his wife immediately before kicking the bucket, that kid would still be able to receive something from their father's works until they reached adulthood.) And if they don't have any apparent next of kin, it just expires at death.

But when it's not an independent artist, and it's something like Disney, where that legal entity that owns the property could very well be around forever, I think it's more appropriate to put a hard limit on it, maybe 50 years as long as they're actively using the property- marketing it, selling merchandise, licensing it out, making it available on streaming, etc. and maybe 15 years if they aren't doing anything with it (Again, we can quibble over the exact length of time, I picked 50 it's a nice round number, and 15 because that's how long a design patent lasts and it felt appropriate)

There's of course going to be some interplay between those two categories, an independent artist who's contracted to make something for Disney may retain some rights to that work, so what happens after 15 years? What if that artist is contracted to make something using IP that's about to expire even sooner? What if an independent artist creates something insanely popular and builds a disney-like megacorporation around it with hundreds of other people all creating derivative works from that original thing, does the copyright stay with that original artist to expire when they die or does it become one of those corporate copyrights that expires in 50 years? And if the latter, does that happen automatically when the company hinsts a certain size or how would that happen?

I definitely don't have all the answers to all those questions, but as a general framework that feels fair to me.