[kbenson]

Perl 6 is like Python 3, but they decided early on that if it wasn't going to be backwards compatible they might as well go wild with enhancements and fixes to earlier mistakes. As such, while Perl 6 is seen as a successor to Perl 5, it doesn't obsolete Perl 5. There's still plenty of active development and new features happening in Perl 5 (after a lull in development, likely because of Perl 6).

It's widely accepted at this point that the name could and would have been better off as something else, like Perl NG (there is good reason to want to retain some Perl mindshare, it is very related at a language level) or something, but by the point that was realized the damage was done. People still argue over whether they should change it to clear this issue up for the layman, but there are good reasons to not want to give up the long past associated with the Perl 6 name.

It's becoming slightly less important now that Perl 6 can now inline a lot of Perl 5 code and modules (including modules with compiled code)[1].

1: https://github.com/niner/Inline-Perl5