Kent, one reason is that the other materials at student locations in conjunction with course mentoring and pacing via internet is a practical model. Of course a great deal of DL is being offered on cable tv and local access outlets. My fingers are tired. The questions of sustaining and scaling up are really critical ones. Let me address one at a time.
Lets try scaling up.
First, there is no need to scale up if there is no demand. So we have to surmise. I suggest there will be large demand. Perhaps less for those who want to get on their own away from home and meet a mate. OK, then we need to scale up.