my bet is that they locked themselves in because of some contract with corporation (trying to beat RIM at some time) or government.
And those contracts are still giving them money, otherwise they wouldn't think twice about breaking it. All apple actions can be directly translated to immediate profit goal.
That must be why Apple is still providing cheap OS upgrades for my four year old Mac. Or maybe they're smart enough to realize that I might not buy their products again if they were obsoleted as soon as possible?
And those contracts are still giving them money, otherwise they wouldn't think twice about breaking it. All apple actions can be directly translated to immediate profit goal.