Asynchronous learning will definitely play a major role in the future, as will a more fine-grained graph-navigation approach, because there's a wide spectrum of the world population for which the September-May, two-semester academic calendar doesn't make sense, but the problem is that it's hard to integrate testing (and certification) into that. Answers to exams will appear on the Internet at some point in time, so the exam questions will have to be refreshed continuously.

Academic honesty is probably the biggest hurdle that online education is going to face. Once grades for these courses start to matter (and at some point, they will) there will be people in the world who will try to cheat.