Yes, the foundation of all software licensing is copyright law and as such all such licensing becomes null and void once it is in the public domain.
However, given that the copyright horizon is only up to 1928 in the US, you've got a ways to go before that is even theoretically a concern.
There was a window of time in which works had to be registered to have a copyright, which is where some of the later surprisingly-public-domain works come from, when the registration wasn't done or wasn't renewed properly. It's possible that some software in that era could be unregistered. However, I'm having a bit of trouble finding a good term for that era and so I can't quite look it up to see if it overlaps a period of time in which software might exist. Any help appreciated from respondants.
Of course, for that to even matter, someone has to have a copy of the software to actually put into the public, and software utility without hardware to run it is pretty limited.
Yes, but odds are you won't live long enough to see anything useful. Mel's blackjack program https://en.wikipedia.org/wiki/The_Story_of_Mel from the 1950s might escape before you die (depending on how old you are), but it strongly depends on the specific architecture of a computer and so isn't useful.
There is probably a lot of software from then that isn't copyright. Back then you had to register copyright or you didn't have it - often that wouldn't have been done. Then you had to re-register the copyright, which given the software wasn't in use anymore wouldn't have been done. Both of these factors do not apply to modern software (at least not in most countries)
That's what abandonware was all about. If you don't support or sell the software any more, it becomes public domain.
But it was a idealistic view not accounting for the future. Today you can run virtualized anything anywhere. The software companies can claim 80s software still being usable because they can deploy it that way.
We considered that console game ROMs will become public domain because once the console lifecycle is over, no original proprietor earns a dime. It's all 2nd hand sales from there on. But, today you run these via their virtual console products and they still make money off them, so public domain is off limits.
In no jurisdiction, it was the motto behind abandonware movement.
All of laws, this one, IP laws, everything concerning software is far too simplistic.
Tho if you want to dance in the grey zone, universally I think it's worthless for a company to sue you when they can claim no damages. This is why old software piracy sites exist by a shovel. If site owner and hosting doesn't care about cease and desist letters and just routes them to spam, the lawyers sending them know they cannot actually mount a case. Else they have to explain how $0 of projected damages is worth court's time.
Yes. In the US this happens 95 years after the initial creation of the software. Many other countries match this time period. Other countries may recognize a shorter copyright, but I believe no country will recognize a longer one.
What exactly happens in 2100 when AutoCAD 2005 goes "public domain" but the company does not need to provide the source code, there is no licensing server available, dongle support, whatnot. Also the company still retains the AutoCAD trademark so you cannot legally distribute modified copies of 2005 if they still contain AutoCAD/Autodesk branding in them.
That's for 2005. For today's software that depend on connectivity, nobody gets anything if the clients are pushed to public domain. You still lack the entire infrastructure. The server code is not a product, its a service implemented by the proprietor, that's beyond this law.
