As technology finds new ways to improve efficiency and make in roads to education, I think the demand for teachers will shift to the left. There will always be a need for teachers, but not on the scale you see today. The WSJ has an excellent article.
At Muscatine High School, Rosetta Stone is being used to teach Spanish. We still have a teacher in the classroom, but the same technology could be used to replace me. I am learning how to draw from a video course I bought from an artist in Australia. The results have been satisfying. On iTunes, there's a university, MIT and Yale both have open courses that can be taken for free. YouTube has rich instructional content. Simple Google searches provide answers to complex topics.
I think that technology will erase much of the demand for teachers but society will not accept that and will continue to institutionalize students in an academic setting.
Comments posted on LinkedIn show aspects and angles of the debate. Some are partially posted below:
Great teachers do more than teach a subject, they help shape a life.
As for science and math teachers .. in classroom experience will be essential especially since lab work is a core part of those disciplines.
If anything, online material will help students advance quicker to the part where the teacher is able to help with significant improvement in their playing and the expense for lessons becomes justified.
As an educator I believe that it's never about the content of what is being taught but rather the substance. Any person presenting material must find ways to engage with their audience.