This isn't a problem. If I start a MOOC and don't finish, I have gained a little knowledge and lost nothing. College completion rates are a problem, because if I start college and don't finish, I'm saddled with thousands of dollars in debt and no degree. Completion isn't a problem with MOOCs, it's an advantage of MOOCs.
Missing out on the other aspects of college life is a mixed bag. Networking and lab work are definitely downsides to MOOCs, but these are potentially solvable problems. But there are serious downsides to college life too. I won't be sad to see the binge drinking and sexual assault culture of "greek" life die out, and I'm not going to shed any tears for sports stars actually having to focus on academics.
But the real crux here is that if trends continue, the cost of college is going to make this all irrelevant. It already is for many people: the author's quote that most students graduate with $30K of debt, as if that's a trivial sum, shows a stunning lack of awareness.
What none of the author's facts capture are the students who either don't start or don't finish because of cost. Tuition keeps rising and financial aid continues to be inadequate. There are only two solutions I see to this problem: funding gets better or we go with MOOCs. MOOCs aren't a perfect solution, but it may be the only solution we get.