Eventually, all of us will become dated. Our industry changes so fast and can be so specialized that its easy to imagine getting stuck in a place where all you know is what you do.
I think that the key to fighting that tendency, is to keep learning new things even if you think the premise behind them might be silly. When something like CoffeeScript or Node.js comes out, before you decide against them because they aren’t what you know, try them. You’ll be pleasantly surprised, and if not - at least you’ll be speaking from experience.