You can co-exist. That's the best path forward for breaks IMO.

Rust does this with "editions". That's where they can make breaks to the language. 2021 can still call 2017 edition code.

Perl actually had this as well with Perl 5. You could specify the version of the perl file and work from there.

Why they didn't do that with 6 was entirely bizarre. They basically promised to throw out all of CPAN with the next perl version.

To be fair, you still have a choice to start new projects in (still progressing) perl 5 or in perl 6. Perl 5 is not abandonned.

I second your perplexity on perl 6 vs CPAN. I still don't get it. It's still a problem.