When all phones are required to be unlocked on demand, you can kiss the $99 or $199 iPhone goodbye. They'll START at $499 or $549, to reflect the true retail value of the phones. It's locking that makes subsidized prices possible.
Huh? That's what the contract is for. An unlocked phone doesn't get you out of the contract, that pays the subsidies.
Even if the phone is unlocked, and you switch carriers, you still have to pay your original contract.