PCs and the Internet are powerful tools. Personally I am skeptical of the extreme claims for technology. However, that is not a crucial part of my argument. Let us suppose that future 3-dimensional holographic projections and high bandwidth networks do make distance learning so effective that live lectures can be phased out. Even then, I believe teachers will still be employed to provide other types of instruction.
Technology can replace many teachers in their present roles.
If all we cared about was to produce what the current system does, we could indeed operate with fewer people. However, new demands will arise to take up the slack. There have always been demands for more personal attention from teachers than could be met, and those demands are likely to increase with increasing world-wide competition. Education is not a matter of getting to where the Joneses were 10 years ago. It is more a matter of trying to get to where the Joneses are likely to be 10 years from now.