Perl 6 sounds like it's still a fair way off, and 5 will be around for a long time after 6 arrives, so continuing to learn Perl 5 is definately not a lost cause. That said, I don't know of anyone who doesn't have additional things to learn as well.

Using myself as an example, I feel I have a decent grasp of Perl 5 basics. I still don't know 94 ways to use unpack, and don't intend to spend time learning them anytime soon. This isn't to say that I wouldn't value that knowledge, only that there are other areas I'd rather learn more about first.

I can quickly look up most parts of Perl 5 that I don't understand very well as I need them. As for broader concepts such as programming theory, I believe learning other languages contributes more to my understanding than learning Perl in greater detail would.

So, as I see it, my current level of Perl knowledge is good enough that learning Perl 5 isn't my highest priority anymore. This may be different for you depending on how extensively you use Perl, how well you know it, and what other areas you're interested in learning more about.