I mean nobody says the same about Julia, which has been in development for the better part of a decade.
The only way it could be too late is if it doesn't do anything better than a single other language. By that I mean if there is a language that does everything that Perl 6 does, and does it just as well.
Even if all it does is bring a collection of useful features that haven't already been collected together into a single language, then it isn't too late.
It could also create a new design of an existing feature that goes on to influence the design in future languages. That would also make it so that it isn't too late. (I think that in the future we may be able say that about Perl 6 grammars.)
I think the real reason people keep saying that about Perl 6 is that they want it to be true. We can only really make that determination years from now when we have perspective.