The rub in these agency deals is what happens if the affiliate goes off the air and who makes that call. The agent (in this case NBC) might want to hang tough to get a better deal, but the affiliate will be the one losing the lion's share of revenue during the disruption. How this intersects in a potential deal with Comcast? That should be interesting.
NBC, Affiliates Iron Out Blanket Retrans Deal (Broadcasting & Cable)