Ahem. It seems that Verizon signed a contract to buy and pay for a certain number of iPhones, no matter how many they actual sell. If this story is correct, then Apple actually has them by the balls and can squeeze hard whenever they want.
The two possibilities are a massive push by Verizon to sell all the iPhones they can sell at any cost, or Apple becoming a majority shareholder in Verizon.
You're being a bit short-sighted. While Apple may have Verizon "by the balls" this time, what happens to Apple the next time they want a carrier to make a significant purchase commitment? The carriers were already trying to push for lower subsidies etc and this event adds fuel to the fire. Apple will get push back and will likely have to settle for a lower figure...unless they come out with something truly "amazing" or "magical" in which case they'll have the upper hand again.