PHP isn't perfect at all, with all its inconsistencies and counterintuitive constructs, but it works great. Lots of libraries you can install with Composer, most people know at least some PHP.
On top of that, unless WordPress isn't rewritten in a new language (which won't happen) PHP won't go anywhere.
Perl is fine, too. We solve problems for clients who pay us to get the job done, not be brag about how we use the latest, coolest technology.