First, "in his recent book" refers to his 2011 book . And Christensen has been prophesying this general bankruptcy "in the next decade" since that time. 
In any case it's interesting to think about the larger argument of the future of traditional higher education in general versus online education.
Bryan Caplan's thesis that (the state should cut funding for higher education because) higher education is mostly about signalling 3 things is a good tool. He argues that higher education signals a combination of intelligence, conscientiousness and conformity. The combination of the 3 is crucial for the model. 
Online education, and more generally self-education, fails on the conformity side. Companies do not want in general to risk such non-conformists, when they can hire from a stream of fresh graduates (smart, hard-working and relatively conformist).
Also, I think the socialization, friendships and networking that happen in the university are extremely valuable and not easily replaced by online education (where and with who can a smart, driven 18 year old hang out while studying and learning for 4 years on MOOCs and textbooks?)
And in addition, I hope, traditional universities are starting to improve their teaching methods (eg, flipped classroom, peer instruction) to multiply the pedagogical and motivational value they offer vs MOOCs.
For online education to replace traditional higher ed, it might require taking into account these factors. Could something like workspaces for freelancers or remote workers - but for studying - replace the traditional institution and the above benefits? Such that, for example, you would not be seen as an extreme non-conformist by not enrolling in a university?
Also, outside the US, tuition costs is often much lower. An online STEM degree, say a certified online masters in software engineering such as coursera or edx, could easily be more expensive than regular (or even the best) university.
(To be clear, he argues that from the individual's perspective, university is still net positive, if you have what it takes to finish the degree and don't get too much in debt. It's the state that should cut funding since it's inflating credentials.)