Dare I be the first to offer what some may think of as cliche advice: find the language(s) you love working in first, then make money at them (and that might require moving to a different market). I was a data warehouse architect for a while - and was paid more than most of my time as an app dev, but I was miserable doing it. Then I spent time in all layers of .NET (C#), and while I enjoyed it, my passion is really open web tech (focusing on the client mostly). In Nashville, .NET is one of the top money makers for devs, so whenever I discussed moving out of .NET to focus on HTML/js, the conversation always turned to "but .NET pays the bills!" Thankfully I can say that I've landed a job that lets me do what I love, not stressing over "OH man, I have to learn platform X - which I hate - just to the bills." My own personal version of hell would be having to specialize in SharePoint....
I should add that I do appreciate how the article encouraged more than one language, and emphasized that you need to think through how and with what kind of development do you want to make money - not just 'which language'...