That's a possibility, but that calls into question why they had to call this release IOS6 in the first place. There are certainly some improvements, but IOS6 looks like more of a "Snow Leopard" or "Mountain Lion" release than a "Leopard" or a "Lion." If the contract stipulated that Apple couldn't do another "major release", then they could have just call it a minor release and ran out the clock on the old deal. Imagine what another year of development could have done for the Apple maps product. (Of course GMaps would improve in that year as well, and Google has many more resources dedicated to Maps than Apple ever will, but still.)

Obviously "IOS 5.1" doesn't push units the way "IOS 6" does, but from what I've seen, people are more excited about the new hardware than the OS upgrade.