But wait, there is more! You are forgetting the huge warehouses full of receivers, dishes and support hardware for the satellite side which Directv has to pay for plus fleets of installers, other types of employees, vehicles, etc. That all goes away with a pure streaming business model. That's what is causing ATT to go the streaming direction and I've been told by DTV management that a Netflix type business model is a goal. Customers call up, you authorize them and take their money. No truck rolls, no hardware, no problems.
So I think we can all agree that delivering TV to millions of customers costs a sh*t ton of money, whether you do it via satellite or internet...
Satellite has an advantage that changing number of customers at the margin doesn't affect that cost, while more customers for streaming make it more expensive. On the other hand, with satellite's customer base having peaked a couple years ago and now in terminal decline, someday there will be too few customers across which to spread the costs. Assuming you aren't talking about launching new satellites, I think you'd have to be below a million customers before that cost became a problematic - and even then if there are still customers who don't have any reasonable streaming alternative they might not have much choice but to pay a $5 or $10 monthly 'satellite surcharge'.