But now you have manufacturers and retailers depending upon that date- as well as emergency services wanting the bandwidth, and the budget forecasts now depending upon the revenue from the spectrum sale.
I really don't think the NAB has the clout they once had. Too many other interests involved for them to push it back, even if they wanted to. Broadcasters may now be resigned, and prefer to settle on running one broadcast (or even multicast), not two. Shut down a transmitter, cut the electric bill (a major expense). What would they have to gain by putting it off again?