I agree with your gist of "keep learning", but some of what you say about obsolescence of knowledge seems overstated to me.
> The languages you learned? Gone.
I'm not sure if I'll ever get to write Modula-2 again. But every few years, knowing some PostScript can come in handy. FORTH has a tendency to pop up on every resource constrained platform for a while. Tcl has preserved some niches.
And C++ is both old and new technology. Some details have stuck around for 35 years, but if you don't reinvent your style every 10 years or so, you risk becoming obsolete.
> The APIs and weird hardware limitations? Irrelevant.
Hardware limitations tend to come in cycles. Just when resource constraints on macOS seemed irrelevant, along came iOS with its murderous daemons baying for the blood of resource hungry processes. Just when resource constraints in iOS seemed irrelevant, along came watches.
And a Commodore PET with its 7167 bytes of available RAM and fairly accessible hardware ports has some similarity with an Arduino Uno.
So while I think it's unwise to bank on some knowledge never ceasing to be useful, or that no new technology is ever worth learning, knowing old stuff in itself is not a drawback.
> The languages you learned? Gone.
I'm not sure if I'll ever get to write Modula-2 again. But every few years, knowing some PostScript can come in handy. FORTH has a tendency to pop up on every resource constrained platform for a while. Tcl has preserved some niches.
And C++ is both old and new technology. Some details have stuck around for 35 years, but if you don't reinvent your style every 10 years or so, you risk becoming obsolete.
> The APIs and weird hardware limitations? Irrelevant.
Hardware limitations tend to come in cycles. Just when resource constraints on macOS seemed irrelevant, along came iOS with its murderous daemons baying for the blood of resource hungry processes. Just when resource constraints in iOS seemed irrelevant, along came watches.
And a Commodore PET with its 7167 bytes of available RAM and fairly accessible hardware ports has some similarity with an Arduino Uno.
So while I think it's unwise to bank on some knowledge never ceasing to be useful, or that no new technology is ever worth learning, knowing old stuff in itself is not a drawback.