You have it backwards. Perl 6/Raku is a completely new language, the mistake there was to call it "Perl". Perl5 on the other hand has handled its evolution much more gently than Python 2 -> 3 did.
First, Perl will support multiple syntaxes that map onto a single semantic model. Second, that single semantic model will in turn map to multiple platforms.
Multiple syntaxes sound like an evil thing, but they're really necessary for the evolution of the language. To some extent we already have a multi-syntax model in Perl 5; every time you use a pragma or module, you are warping the language you're using. As long as it's clear from the declarations at the top of the module which version of the language you're using, this causes little problem.
There were even plans for a translator [2] similar to Python's 2to3 tool
Larry Wall and others are already working on a Perl 5 to Perl 6 translator, which will be able to translate (most) Perl 5 source code to the equivalent Perl 6 syntax.
In addition, Perl 6 will provide a "Perl 5 compatibility mode", allowing the compiler to directly execute any code that it recognizes as being written in Perl 5.
Integrating Perl code in Raku can be done with the excellent Inline::Perl5 module (https://modules.raku.org/dist/Inline::Perl5:cpan:NINE). In fact, that efficiency of that module basically killed the "parse Perl code in Raku" project.
It gave me at least a false sense of thinking Perl 5 was done and going to be replaced.
At the same time I found Python to be much easier to write, maintain and I became attached to the structure that PEP provided.
There were a lot of other factors that made me switch, but that particular point of not calling Perl 6 Perl made me think.