This is not entirely unlike that. Somewhere along the way, everybody realized Perl 6 was not the path forward from Perl 5, and so Perl 6 never really took the place of Perl 5, just like PHP6 never took the place of PHP 5. It looks like a pretty similar scenario, if you squint, I think.

It makes little difference for Perl that this experiment in a next generation version of the language is still alive and going its own way. The result is the same...people kept moving forward with version 5, and if it needs a new version, it can't use version 6 because 6 was already used for that other experiment (that failed to take the place of Perl 5).