So *I* who am careful to write readable and safe code, have to use a non-preferred language preference b/c someone else cannot handle using it properly?!

Sadly, that is the realization that I have come to as well. A chain is only as strong as its weakest link and all that... but no, really, that's true, b/c modifications are likely to be made at some point (kinda biasing towards production there but even so, answers with perl one-liners on e.g. StackOverflow are ubiquitous, but someone would have to know the language to be able to modify them to suit their specific use-case, so also not at the same time).

Fwiw I really did not think that Perl was hard to learn - though that was coming from the likes of assembly, various Basic styles, C/C++, and having already learned regular expressions via Unix e.g. grep and awk and sed. "Regular expressions" are quite a steep learning curve, though that's not the same thing as Perl, and quite frankly Perl is the undisputed (iirc?) master of them all, so whether someone wanted to write Perl without those, or wanted to do try to do regular expressions without Perl, either way Perl seems good for having included regular expressions, not something to penalize the entire language for. Also, C/C++ (and Rust) has a bit of a known learning curve as well...:-) Though indeed it's entirely fair to say that if someone were to pick just one language, then I would be hard pressed to find any justification for that being Perl. C/C++, Java, Python - all of these, depending on the situation, are fine choices, whereas Perl is absolutely niche.

But even so, why would it follow that it would necessarily be a good thing if Perl, or let's say awk, would fully "go away"? I kinda see Perl and awk as being in the same boat these days - both niche and powerful, yet both steadily becoming obsolete? Just b/c something else is "better" doesn't mean that everything else must die. Except, as you mentioned, for reasons of collaboration and thus code-reuse. Even there though, putting all of our eggs into a single basket scares me: what if tomorrow Microsoft, or Google, decides to purchase the rights to Python and suddenly control that entire industry sector in one fell swoop?