Let's do some math.
At my university (one of the biggest in Poland), there were 150 people majoring in CS per year.
According to the article, an average MOOC enrollment is 50.000. Let's assume 10% completion rate.
That's 5.000 people. It would take my university 33 years to graduate that many people (assuming 100% completion rate).
The cost per person? Several orders of magnitude smaller per student for MOOC.
Scalability? Almost effortless for MOOC, almost non-existant for the university (to double the number of students they would have to double the number of professors, double the number of buildings etc.).
What happens when you fail? At MOOC, try again. At university - you're out.
There are many reasons why completion rates are much better at university (you paid for it, you value it more; more external pressures (your peers, your parents), motivational support from your fellow students; the way you think about it (university: I have to do it or else it's really bad; mooc: no biggie, I can always do it again).
MOOC destroys traditional education at almost every other metric.
It's a classic Innvator's Dillema: a product that is not as good as what exists but so much better at some important things (cost, convenience) that it'll grow like weeds and will become better at things it's not good at (like retention) faster than incumbents becoming better at matching MOOC at price, convenience.