I think a debate about Khan's specific videos is beside the point. For years, people have been talking about online education and we got these dreadful videos of a professor lecturing, shot from the back of the room. Khan shows us a realistic vision of how online education can happen at reasonable cost. It will not necessarily replace the teachers, but it will replace a teacher who repeats the same material multiple times a day. And it will help to level the playing field.
People in universities are talking a lot about is the "flipped classroom", which means the lecture is online and clarification and working of problems occur in the classroom. This model is most obviously applicable to STEM classes, and if you haven't been following the developments, this site at NC State offers an overview of what's going on with one kind of flipped classroom and where it's happening. The University of Minnesota has recently made a huge investment in this kind of classroom.
Whatever happens with Khan specifically, he's energized a process of transformation that everyone knew had to happen eventually. Kudos to him.