Those aren't necessarily untransferable skills. You can always bill yourself as being able to get up-to-speed on a new codebase quickly and pitch yourself to corporations that need someone to battle their existing, horrible codebase. They need people that can be productive within their codebase.
An additional plus is if you're good at pushing incremental change to the existing codebase to get it under control. (e.g. my company has a large pre-existing Perl codebase, some of which mirrors functionality of various modules/packages on CPAN -- some better, some worse -- and there is a lot of internal push to move towards things like Moose, Try::Tiny, etc where possible for newer classes, etc)
An additional plus is if you're good at pushing incremental change to the existing codebase to get it under control. (e.g. my company has a large pre-existing Perl codebase, some of which mirrors functionality of various modules/packages on CPAN -- some better, some worse -- and there is a lot of internal push to move towards things like Moose, Try::Tiny, etc where possible for newer classes, etc)