Programming languages don’t “die.” (They don’t even “fade away.”) Instead, they become the foundation technologies of mission-critical applications ... which may literally be worth millions of dollars to the businesses who own them.
Even more significant than the language is the ever-growing library of contributed material ... in the case of Perl, that is CPAN. This, in whatever language, truly becomes far more important and significant than the language itself, even though language and library are often spoken-of together, e.g. “Ruby (language) on Rails (library).” In practice, you may well select a language mostly to get your hands on a particular library.
I also think that it behooves you to spend a lot of your time looking at languages. These are the fundamental tools of our trade, and they are constantly being invented, and there is a reason for each one of them. You can indeed learn a lot just by watching the various sets of videos that are out there, being five-minute introductions to Perl, Erlang, Haskell, haXe, R, Prolog, and a whole bunch other tools that maybe you never knew existed. Yet. Stick those ideas in the back of your mind because you just never know when they might bear fruit. (I also happen to find the exercise to be both eye-opening and great fun.) But at the same time, never dismiss the “old.” If they managed to become old, it probably means that they are considered by many thousands of people to be reliable. It is part of your trade (and a huge competitive point in a tough job market) to be at least cursorily familiar in advance with the tools of your trade.