KA only replaces teachers if it is competing to serve a need already filled. KA is far more impactful in filling a need that is NOT already being met for its population.
The biggest problem in education is that it doesn't scale well. Individual attention might be "best" but it requires access to a great instructor who can tailor instruction to the student. Sub-optimal teaching methods (like KA) take a different approach. It might not be the "best" way to teach an individual, but it might be the "best" way to teach a large group of people.
KA is creating a partial substitute for teachers. Instead of creating more teachers, KA is reducing the need for teachers.
You are correct, however, that the 6'th biggest political donor of all time is likely to go to great lengths to avoid being replaced by machines.
http://www.opensecrets.org/orgs/list.php?order=A