In the beginning, the iPod let you listen to every CD you owned, even when you were stuck on the Red Line. Then Steve Jobs said, "Let there be video," and lo and behold, you could watch "Lost" die a slow, overwritten death on a two-inch screen. But while people seem content to load their little devices with as many songs and TV shows as possible, podcasts (think of them as radio programs that you download) tend to be neglected.
Listen and Learn With Podcasts - washingtonpost.com
The Answer = Not anytime soon
Why? it all falls down to the mentality of the person learning and the fact that listening to a podcast is a passive occupation, were as good learning will always be active.
Increasing technology use within schools, colleges and university's can do nothing but help the way we learn and consume that learning materials. Being able to access course materials 24/7 is a great resource to have but you don't remember the stuff you do aswell as you would from a classroom.
I think there will inevitably be some invention that takes podcasting and vidcasting out of the passive domain into the interactive and maybe then we can consider replacing the classroom. Until then I think classrooms are safe.