by creating a new community in parallel, you will most surely split the current community.

Maybe. But this is why I do not believe we need to worry about it:

The "Perl community" is already split into multiple fractions. As a PerlMonks fan, I'd like to think that this site is the nexus of the Perl universe, but there are plenty of Perl users out there who do not see it that way. Some have tried PerlMonks and found it not to their liking, for a variety of reasons. Others have never heard of it at all, or are unable to take advantage of it for one reason or another. Some people prefer the bloggish style of use.perl; some like mailing lists or good ol' usenet groups; some like wikis, some like irc channels, some like bulletin-board-style forums, some like the modern gadgetry of StackOverflow. Some prefer the quaint meatspace interactions of PerlMongers meetings.

But you see, there is nothing to prevent people from participating in more than one of these venues, or even all of them. There is quite a bit of fluidity of membership across this spectrum, and altogether they constitute the real Perl Community. Having another site which "does PerlMonks" but does it better is not a threat to the community. Quite the opposite: it would, I believe, go a long way toward assuring the next generation of perl hackers that Perl is modern and relevant.

If the current PerlMonks goes into decline — and the numbers clearly suggest that it already has — it is almost certainly a trailing indicator that Perl 5 itself has gone into decline. Perl 6 represents the new lease on life for the Perl legacy; I believe it makes sense for the Perl 6 user community to be hobbled by a web site which is only a couple years behind the times, rather than one which is a couple decades. ;-)

a new and improved framework might also be beneficial for the current site

Now, I will say.... My proposal is very much about using the Perl 5 ⇒ Perl 6 transition as an oppportunity and excuse to build a New PerlMonks. We could, very possibly, allow Perl 5 content on the new site. This would allow the site to be the PerlMonks NG which many people have been dreaming of for a while. But I think it would be important to make Perl 6 the primary or default language for the site. Perl 5 would be the "also ran", the ugly stepchild, much the way Perl 6 is on this site. The primacy role would be reversed. But, on the other hand, depending on how the site is designed, such role distinctions might not even be necessary.

why not import/migrate all nodes from the current site? The new Perl(6)Monks could have an (as you put it) archeological Perl section

I don't think we'd want to do that as long as the content of PerlMonks is a moving target. Once this PerlMonks ossifies, we could do that... but then, why not just leave it running, to act as its own archive? (fossil, as it were.)

Thank you for your other comments.