Virtual Growth Projects has an interesting essay on the economics of on-line learning. The essence of the idea is that the teacher/student relationship in the on-line world has allot in common with the economics of file sharing:

The seed/leech terminology is borrowed from file-sharing where a
‘seeder’ is someone who possesses 100% of a file and is in a position
to share it with others. A ‘leech’ is someone who does not yet have
the file, and hence cannot share it.

• a knowledge-leech has not yet achieved mastery of the subject
• a knowledge-seeder has achieved mastery (and hence is in a position to share it with others)
• knowledge transfer is converting leeches to seeders

The knowledge-transfer process creates ‘seeders’ who are capable of
productively contributing to it.

Given that the best way to demonstrate understanding of a subject is the ability to teach it to someone else, it seems plausible that the business model that on-line education is likely to gravitate towards is one where students evolve into roles involving teaching, essay grading, exam question writing, etc as they gain mastery of the subject that they are learning. Success in your studies would, in this model, act as a sort of currency that would allow one to recoup some or all of the up-front costs involved in taking a course.

It might also take us away from the traditional production model of pedagogical contents–expert writes a text book and course materials–to one of edited but crowd-sourced content, much like Wikipedia.