My point of view is that Perl6 is not so much a successor to Perl5 but rather an alternative to it. To that end it might have been preferable not to call it Perl6 but maybe something like PerlVM that would indicate that it takes a radically different approach to "classic" Perl.

If/when Perl6 does reach release-level maturity it probably won't supplant Perl5. The two can quite happily co-exist as different implementations which share (most of) a common syntax. At that point we can all choose the right tool for the job at hand.

Just my tuppence.

Update: It's now October 2019 and "Perl6" is now "Raku" so that, belatedly but thankfully, solves the naming problem. The syntax is probably more divergent from Perl than I anticipated but the two languages (and communities) can now co-exist and provide two different tools for every programmer.