In my opinion, Dart is the first browser side language, that has any possibility of changing this monopoly. I don't think that it's a good thing that JavaScript is the only language you get in the browser, but that has nothing to do with dogma (I coded a lot in JavaScript, and it has it's place).
As stated below, I will probably remove this Introduction, since it seems to distract from what this article is about. I hope you consider reading the article anyway.