I wondered how he didn't see this coming from a mile away, but in looking up more about Sal Khan himself, the surprising thing is that he never had any 'normal' teaching experience, and that explains everything. In a normal classroom, good kids don't need teachers. You could give them a book (or some Khan Academy videos, or a reliable LLM) and they'd learn the material far faster than you can teach it. Now let's talk about the other 95% of kids...

Those other 95% are going to generally have either a lack of motivation or a lack of intelligence. And for these kids a good teacher can do a lot, but actually teaching the material itself is a relatively small part of it. It's about giving them that motivation, or adjusting the material for slower students. And most importantly, it's about doing all of this without making it apparent that you're doing this, since keeping it feeling 'natural' is an important part of making it feel interesting and also helping to build a better rapport with the kids. That rapport/connection building is critical, and completely outside the domain of LLMs.