A lot of this discussion is just passed my level of understanding, so forgive me if this is inappropriate. It almost sounds like we're approaching a "Y2K" kind of issue. Even if Perl 6 won't be released for a few years yet (I don't know *what* the real schedule is) when it is released, unprepared perl 5 code will manage to find itself submitted to a Perl 6 interpreter. You can count on it! In the above discussion, it doesn’t sound like Perl 6 will magically know when it is getting perl 5. Don't programmers have an obligation to "do the right thing" now to avoid problems in the future?
Perhaps, though, only trivial code will be affected because all serious code uses packages. Is that's the case, the problems of transition will be trivial.
(so many nodes and so little time ... )