Sometimes corporations die, but the copyrights they hold don't die with them. When corporations die their I.P. gets purchased by someone else (usually another corporation), so it never ends. A popular IP which gets locked up by a corporation for 100 plus years is a bad thing, but you know what may be even worse? When its a niche IP that they own but they don't do anything with. That really sucks if you happen to be a fan, because nothing is being done with it by the owners and no one else can legally do anything with it. There are a lot of old video game franchises that are like that. Someone owns them, but they don't do a damn thing with them, and at the same time no one else is allowed to either.
So I think if you aren't going to do a damn thing with something it should be fast tracked to public domain status. There should be like a period of 5-10 years where you can do something with it, but if you don't in that period of time then it should automatically become public domain. That way someone else has the ability to take it and run with it. But if you do something with it, then that should renew the copyright for it and so on until death.
A good analogy to this is the countout rule in wrestling. If you leave the ring, the Ref starts counting to 10 and if you don't get back in during that time you lose. But you can circumvent that rule by quickly going in and then leaving again. That will reset the countdown. Copyrights should be something like that. The moment you stop doing anything with it, the clock should start ticking, and you have until the time runs out to do something or else you lose it.