The best schools will still be brick and mortar, because the best teachers will still want to interact with their students in person. I might peg community colleges at being the first to take a hit from online competition, except that their low costs and geographic convenience make them just as easy to attend and more rewarding intellectually because of the face-to-face interaction. We are social animals; technology will not change that.
Online is probably a sensible option for professional degrees, continuing education, certifications, etc., but I really don't see the best and the brightest skipping four years of University just for the sake of convenience. There is a huge difference between a degree and an education. It's much harder to get an education when one is still immersed in one's own familiar world.