Well, you'll find business is not that simple. Consider this, In that time I may see an Android phone I like and jump ship. That's then a 2 year lock out during which I won't return to iPhone. Further, having finished my contract by the end of this month, that means they're not taking a cut of contract revenues from me until I get back on, if I ever do. They've effectively lost a customer, along with the cost endured to acquire said customer.
It's the carrier that's been paying back the subsidy from your subscription fees under contract. Apple got their money up-front from you two years ago. Any extra revenue they earned from you was from iTunes/App Store sales, which I'm guessing will probably continue after the contract is over.
You also said you're waiting with your cash in-hand for iPhone5, so looking at competing Android phones isn't even on your radar. Tim Cook loves customers like you.
