I think you're trying to solve the wrong problem: Don't move the languages further apart through rebranding, move the implementations closer together through improved interoperability.
Have a frontend that can invoke the perl5 interpreter as well as Rakudo as appropriate, supporting the perl5 command line flags, and arguably quite a bit of the problem goes away.
Maybe the problem isn't with the "Perl" part of the name, but with the "6" part? It sounds like an incremental update when it's actually a new language.
Have a frontend that can invoke the perl5 interpreter as well as Rakudo as appropriate, supporting the perl5 command line flags, and arguably quite a bit of the problem goes away.