I think you worry too much. It will probably follow the same pattern as most software: it comes out, early adopters try it, eventually it either catches on or doesn't. No reason to stress about it.
As for what's "so wrong" with Perl 5.x, it's more a question of what could be improved in Perl 5.x. People listed their ideas in the Perl 6 RFC process, and you can read about them in Larry's articles on perl.com.