Here's a better phrasing:

In 2013, a software company can choose to become a pure Javascript shop. There are good solutions for app writing in Javascript for web, mobile, desktop and server. They might not always be the best solution, but it's becoming increasing difficult to argue that they aren't good solutions.

That might be a good choice for a company to make; but is it a good choice for an individual? Do you want to be limited to pure Javascript shops or stuck in a role in a mixed shop? Do you want to completely miss out on all the benefits that learning new languages bring? For example, you could learn Oberon to make your object-oriented Javascript better and learn Haskell to make your functional Javascript better.

Another hyperbolic article headline that the article's body doesn't -- and can't -- support.

...This has got to be the most idiotic article I've ever read. Does this guy realize that there exist fields other than web development? Sheesh.

I think it would have been wiser to point out that knowing JavaScript means you are pretty much guaranteed a job in 2013. It doesn't make the other languages irrelevant, but it makes you relevant in the workforce. I still come across tons of graphic designers that can barely code HTML and therefore have to push their designs over to a front-end developer of some sorts who does a little bit of jQuery "magic".

lol.