If this is true, this is a very ballsy move on T-Mobile's part, and would probably explain how they're able to afford to offer the iPhone in their current financial condition. They simply won't subsidize it like most other US carriers do. Isn't Virgin the only one that doesn't?
http://bgr.com/2012/12/06/t-mobile-smartphone-subsidies-end
I'm not sure if the majority of consumers would understand the concept of paying $649 for an iPhone that other carriers are selling for $199, even if they do get to pay for it over time.
They've been doing this for a while now with their Android smartphone lineup. It's actually working out well for them and they've already moved around 80% of their postpaid customers to this Value Plan model. It basically boils down to them breaking the phone price up to make it a separate charge from the actual rate plan. They charge $70 per month for their truly unlimited data plan, add in the $20 per month EIP for the phone and you come out at $90. Difference is that after the phone is paid off you get an extremely low priced bill compared to the other 3 carriers.