Python is everywhere. The amount of python code that is written every day is staggering. It will be there 30 years from now doing the same thing and people will be looking at that code like it's COBOL.
Perl is extinct in comparison. It's not been used for any projects anywhere for a long long time.
Which is a good example that the decrease in use can go a lot faster than you think. Perl was widely used in 2000, and thought to be on par with Python. Similarly Visual Basic which nobody seems to remember any more.
Also, COBOL is simply used because it is uneconomical to rewrite those old programs, not because it is a good language to write new stuff in. But the heavy dependency of Python programs on libraries hosted across the web means that obsolescence can happen a lot faster today; a COBOL program is almost totally self-contained in comparison.
Widely used is relative, Perl at its peak was used in relatively small applications and short scripts.
I worked at the largest US bank and had the unfortunate task to decommission the last Perl software. Doing a lot of archeology there was never much of Perl really, some short scripts here and there. One or two flagship applications in the early 2000 but they were rewritten long ago.
Looking at our python codebase however, that's ten of millions of lines of code covering all types of applications and all aspects of the business. It will still be there 30 years later.
The dependency to the interpreter and external libraries is a problem indeed. They're constantly shifting or getting abandoned under your feet. I wonder how this will be managed eventually.
Is this wishful thinking?