The question of still needing teachers seems to come up each time I run a course like this, although rarely is the case stared so eloquently and objectively.
Virtual reality environments are very engaging for some students, while other students just don't get it. Game playing is virtual environments is very engaging and seems to engage many more students, particularly where the game involves teamwork as in Massively Multiplayer Online Gaming.
Artificial intelligence has also come a long way as the processing power of PCs has increased. Once computer storage and processing power approaches that of the human brain it is possible that computers could think for themselves and learn. When this happens it's possible that to some extent the teacher could be replaced, to a degree, by the technology. This is still some way off yet I hasten to add.
My own view is that the role of the teacher is changing from the expert in discipline knowledge and skills to a guide, mentor and learning designer. I'm not sure that a computer will ever be able to understand a students' fears, concerns or aspirations the way a good teacher can. There are also particular skills that are best taught in person.
I think that we teachers will always be required, but our roles will change as the technology evolves.
Thanks for the question, and I hope our colleagues venture their own opinions as well.