No. There is any chance Comcast will add Voom21 or Voom10. No way. They can't even add TNT-HD here in San Francisco on an 860mhz system. So forget that.
To me, it's simple. The copper wire in the ground has a maximum capacity and will cost oodles to take to each customer's doorstep. Wireless bandwidth continues to increase, and even the high cost (to we mere mortals) of launching satellites is cost-effective to, say, laying fiber to every door in America.
Yes, cable companies whine about must-carries and analog channels, and yes, they probably did deserve some return on their massive infrastructure investments over the past 30 years or so. But the world doesn't stand still. Your 30-year-old copper wire doesn't cut it any more, or won't soon. Either invest in the future (i.e., get busy laying fiber), or get run over by those who will.
As the saying goes, there are three kinds of people in this world: Those who make it happen, those who let it happen, and those who ask "what happened?"