I have been writing and maintaining Perl code since 1994. The first thing that I worked on was a mail-handling system written in Perl4. I have written production code in both Perl4 and Perl5. I have been playing around with Perl6 for the last couple or three years, just to see what is happening in that space.

Last week I got a note from an old boss at the job I had in 1994. He is now the CIO and he has a contract to upgrade the old mail-handler system into something more modern. They run off the "if it ain't broken, don't fix it" theory; so the last time someone worked on it was when they "converted" it to Perl 5 (specifically 5.6.1) by changing the shebang and fixing the obvious errors.

That mail handler is a non-trivial system (you try parsing email address in Perl4....) that has been in service with out a major re-write for over 20 years. I expect the same kinds of life-spans for properly designed and built Perl5.xx systems. Particularly if the P5Porters continue the work of retro-fitting Perl6 concepts into the Legacy code base.

N.B.: I am actually, seriously, considering coming out of retirement for this. Redoing a Corporate E-Mail system and building it right, this time. (With a proper design, using CPAN modules as much as possible, a real test suite that exercises the entire system, modern hardware with enough RAM, disk and multiple multi-core processors, a real backup and recovery process, plus documentation for everything), is very**3 tempting.