Considering it seems to take almost a decade for Perl 4 to fade (though some still floating around), and Perl 6 isn't a next year thing, and there're 4000+ Perl 5 modules in CPAN, it would be a while (5 - 6 years the really really quickest?) before Perl 5 would go "obsolete." It's not of anyone's interest to retire Perl 5 too soon.

Perhaps you could consider what direction you want to go within Perl 5 instead of across major versions.

Best of luck.