Ever since HDTVs came out companies have been trying to find a way to get HD programming to multiple TVs. The easiest way is to broadcast it and have your TV's tuner pick it up. The problem with that is that is has to be national standard that everyone follows since all TVs would have to use the same tuner and that's why the only thing to do it is local broadcast as far as I'm aware.
As for using equipment in the house to get HD to every TV, it's very hard. A company would have to make a device that outputs each individual tuner through HDMI then the customer would have to have HDMI run to every room in the house. This is not feasible. Dish's solution to this was to use MOCA which allows them to send info over coax which is already the standard in all homes. The only issue with this is that it still requires a device in each room that picks up that signal and outputs it to your TV. Dish at one point made a TV that did all that for you but once again, it wasn't really feasible.
If the industry decided to make MOCA a standard and put that ability into all TVs made then Dish or any other company could just have a host receiver that outputs it's tuner to all TVs than can pick up the MOCA signal. This is, of course, how I interpret it and I could be completely wrong.