Does foundational knowledge disappear? If so, how long does it take until it happens?
We forget how to do things all the time: civilizations, skills, languages. Oh, languages... Many are lost in time. Or rather, they get stuck in time: we know where they are; we just can't reach them anymore—they're stuck there.
The same happens for software. But digital preservation is hard. Have you ever tried running really old software on modern computers? How many computer programs do you own that would work without an internet connection? Do you really own that program?
Some people interact with computer programs but they don't really know how a computer works. I've written C and x86 assembly programs and I know that I do not know how computers work. I know many computer science grads in the same situation: not knowing how a computer works and who've never done science. I did not forget how computers work, I never learned it. At one point, most of the software engineering population will be in that same spot (is it there already?). What happens then?
Most of my family forgot to be self-sufficient in one generation. Before my generation, we were farmers. Now, they know how to cook but do not know how to get food from Earth. The newer generation uber-eats but under-cooks. It only took one generation to forget how to conquer the world woven by nature and another one to forget how to skillfully maneuver the one crafted by humans.
Yes, there are still farmers and chefs around. I am just skeptical about our ability to distribute and preserve foundational knowledge in the constant pursuit of new one.