It won't. If you look at advanced engineering/mathematics
material online it is abysmal in quality of actually "explaining" the content. Most of the learning and understanding of intricacies happens via dialogue with professors/mentors/colleagues/etc.
That said, when that is not available, LLMs do an excellent job or rubber ducky-ing complicated topics.
To your latter point - that’s where I think most of the value of LLMs in education is. They can explain code beyond the educational content that’s already available out there. They are pretty decent at finding and explaining code errors. Someone who’s ramping up their coding skills can make a lot of progress with those two features alone.
That said, when that is not available, LLMs do an excellent job or rubber ducky-ing complicated topics.