Just more bandwidth to go around for more HD. And by that time folks will be on pure EA or WA setups so they can move stuff around at the leisure. The hunger for HD isn't going to stop so they need all they can.
But, since they are going to move the the Core HD Channels to 72.7. When they get the sat. at 61.5 going, will they move the HD Channels back to 61.5 or leave them on 72.7?