Keep in mind that "ripping out Perl internals" doesn't automatically imply that the changes will be externally visible. They could, in theory, completely rewrite Perl's internals from scratch and still make the rewrite pass all the existing regression tests...

Now, to the extent that rewriting the internals gives them the mental freedom to consider an externally-visible change like using "." instead of "->" as an attribute accessor, there's some cause for concern. But given that I believe there's a stated goal for Perl6 to be able to run 95% of Perl5 scripts, I agree with the others about letting the discussions run their course and not worrying too much until we know there's something to worry about.