My kids never went to school. My 3 entered community college at the ages of 13, 12, and 13. All finished Calculus III by the age of 15, and all their college general courses.
My prediction:
Even the brink and mortar college can be dumped for much of the routine stuff ( and that includes Calculus III). There are on-line law schools now, and in my opinion even a lot of medical school could be done on-line.
Government school:
Government schools are NOT about educating children. They ARE about maintaining a government white-collar jobs program for collage grads with the lowest SAT and GRE scores on campus.
With medical and nursing, engineering, and the sciences, there are hands-on lab components that won’t work online. But, as you say, much of the curriculum could be online.