It seems you did not understand why I inserted the "Late, fat, and ugly" piece above.
Firefox eventually shipped working software that people actually use. Until Perl 6 achieves the same thing, I don't take the comparison as evidence of the historical inevitability that Perl 6 must succeed because another long running project eventually succeeded. (I think a better comparison is E17.)
As for your curiously chosen word "evidence", until the point at which any Perl 6 implementation reaches any degree of usability as a product, I reserve the right to be dubious in public and in private at every press release which trumpets loudly that eschaton is immanent. I've helped produce a few of those press releases in the past decade, I've helped produce a chunk of the code, and I even made a very testable prediction about how long the nom rewrite would take back in December 2010 and January 2011 (and it turns out I was right); I think I've earned the right to be skeptical.