Rather than AT&T's method of reducing the cost each month, T-Mobile will drop its $200 fee to $100 during the last 3-6 months of a contract, during the last 3 months it drops to $50, and for customers with 30 days or less left on their contract, they will either pay $50 or the amount of the last month of service, whichever is less.
As I mentioned before, the cellular industry is definitely listening to unhappy customers who feel they shouldn't have to pay a huge termination fee even if they've kept the service for over half the length of the contract. Now that two of the biggest cellular companies are on board with prorated ETF's, there's no way that this won't be a standard practice with any major carrier before long.