I have a strong CPAN offering, and 14 years commercial Perl experience under my belt, but also run a small Perl recruitment company, http://perl.careers/ so hopefully I know what I'm talking about!
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The general state of the Perl market in London is buoyant, but is in very gentle decline; there will be Perl work around forever (there's still good money to be made in COBOL!), but I don't see a Perl 5 revival on the horizon. Companies like [x] and [y] are doubling down on Perl and starting new projects in them, where [z] and others are gently moving away, and others are staying put but talking about the possibility of moving to something new in interviews with my candidates.
If you're enjoying yourself at [current company], it would be entirely valid for you to gently raise concerns with [your boss] about the state and future of Perl there.
In terms of what else to learn, I see a bright future for Go, and also see it as an enabler language. My suspicion is that Perl, Ruby, Python and JS houses will all start to add more and more services in Go; I know of three Perl places either using Go or considering it to go alongside Perl, and get the feeling this is true for other dynamic languages too.
I think that a good Perl/Ruby/Python/JS developer with some strong open-source Go projects would find it easy to find work at a company using another dynamic language who were also considering Go. Whereas there's a CPAN library for everything at the moment, that's not true of Go, so porting over a few simple CPAN libraries over the next few months feels like a good career move.
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Hope that's helpful and not too controversial. If you're looking for Perl work in London, please do get in touch!