I think the silver bullet will be when you can sit down with your own personal Watson have it socratic method you. A really good teacher can find the boundary of understanding and push students to think at near maximum capacity by carefully asking questions just out of their intellectual reach. I think that's the power of lecture and I don't think we're too far from replicating it (50 years maybe?)
Clearly when we have human level AI you can just use those, but depending on energy efficiency and cost of power that may take much longer to be cost effective, even after we have them.
"sit down with your own personal Watson"... "I think that's the power of lecture"
This does not follow. The virtue of a lecture can not be that you are getting personalized optimal Socratic dialog. Only a couple of people in the audience can be getting that at a time.
Optimal Socratic teaching will probably never disappear, but I'm still not hearing a lot of defenses of lectures qua lectures that still don't generally boil down to "It was good enough for me, it's good enough for them".
Clearly when we have human level AI you can just use those, but depending on energy efficiency and cost of power that may take much longer to be cost effective, even after we have them.