(And sometimes these mainstream, practical, everyday skills stick around in funny ways: https://www.hillelwayne.com/post/linked-lists/)
Innovation stalls, improvements take longer to materialize. Machines become obsolete but there's nothing to replace it yet.
Fewer people in fundamental roles is a risk, a danger to our economic chain. We could become quite vulnerable, even crash.
As someone whose managed a team before, there is a minimum population of people practically required to sustain a particular corpus of actionable information without suffering severe degradation in terms of said information's application.
Once one ends up below that point; things tend to go the way "from scratch rediscovery required", until such time as the population of people capable of acting on it is restored.
Whether that actually happens is a prioritization decision balancing against everything else that still has to be done.