There won't be a windows 20, or anything closet to that. If we're still using computers the way we are now in 20 years, then we've seriously failed as a species.
The first wasn't thought about, it was done to save bytes, not because people weren't going to be using the software.
IPv4 was enough, the use case changed.
640K should be enough is an urban legend.
This isn't meant to come across as rude, but you're missing the forest for the trees.
Everyone needs the post office, how else will you be able to send a letter.
Everyone needs news, newspapers will be around forever.
Everyone needs a travel agent, people like to travel. They'll be around forever.
Everyone will always have a land line.
Video stores will exist forever...
Everyone needs a watch...
Etc...
For every example you come up with, I can come up with three in which the majority of the population no longer complies. We progress more than you realize. A commercial windowing computer interface has been around for 30 years next year, it's still in it's infancy. Touch interfaces have transformed digital adoption to numbers greater than I would have ever been able to comprehend back in 92 when I sent my mom, who worked at the University of Calgary while I was at the University of Alberta, an email. It was magical. And yet, in no way did I think it would ever grow to a point where every person would hold not only email, but the internet (which existed, but not really at that point). If you're under 30, it'll be a lot harder to see the rate of increase.