The article has some interesting sections, but whenever someone gets too dystopian about the working class ala "Fight Club" without also talking about quality of life metrics they lose credibility. Think about how cheap things have gotten. An iPod touch is basically mini-computer, game console, portable TV, GPS, Walkman, digital camera, and more for ~$200. How much would all of that cost someone in a time that was better for the middle class? It is a complex calculation, but I'm much more optimistic than the author.
Not only that, but they probably enjoy their job a lot more.
I've never taught Yoga, but I have taught martial arts [1]. It's far more enjoyable than booking airline tickets on a computer, and I'll bet money that teaching Yoga is as well.
[1] Only to total beginners, I'm entry level myself.