A Perl REPL would be very nice, agreed, but I do not think that that would break much code,
It is possible you're right, and that's preferable. But: if I were presented with a first-class repl with completion and introspection, and also acts as an LSP server for $EDITOR, but to get it I had to accept a couple syntax compromises enabled via 'use v7', I'd accept that.
I believe it was one of your initial replies that clarified that for me... the question of the justification/value-proposition. I believe the justification given is: this will help us appeal to new users. I'm not sure that the proposed syntax adjustments will accomplish that. After all, Raku polished several of Perl's rough edges. Where are its new users?
The conversation I'm really not looking forward to is:
Me: "Oh, and we're going to have to make a few changes to the Perl scripts, and re-test them sometime this year." Boss: "If we have to do that, let's just get $new_hire to re-write them in $flavor_of_the_month."