I don't know what language we'll be using to solve
ubiquitous, practical problems 20 years from now, but I do
know it will be called Perl.
That's pretty much exactly my point. There are many other languages out there, and the overwhelming majority of them do at least a few things better than Perl. But Perl has a tradition of embracing and incorporating the good bits, rather than sticking to its guns and pretending that it's way is the only way. (TIMTOWTDI, remember?) So (I contend that) Perl in 20 years may look nothing like it does now, but it'll still be Perl, not some language that replaced Perl's successor.