Since it'll take over 20 years to go from perl 5 to perl 6, I'm sure they're safe using 11.
Having said that it would be pointless to go simply rewrite existing Perl 5 code to Perl 6. A good deal of Perl 5 libraries will be ported to Perl 6. And then Perl 6 will be well suited for a lot of big projects.
Perl 6 has a very nice type system, packed with all the goodies of a enterprise object oriented language,it has powerful functional programming features, and with all that it stays true to its scripting roots.
The right way to look at it is, Perl 5 and 6 will co exist for much of their individual lifetimes.
I gave up trying to find out a while ago.
Great python minds think alike?