1. Assumption #1: T-mobile "has no plans for the future."
You can't possibly know that. If anything, the negotiated spectrum transfer and payout on deal failure is a small indication that they do have some plans for the future.
2. Assumption #2: Any carrier without the iPhone is doomed to failure.
Metro PCS does not offer the iPhone. I don't think they are going away anytime soon.
3. Assumption #3: The government needs to plan for cellular market consolidation in order to benefit the consumers.
Actually, cellular market consolidation is not good for the consumers. Consumers benefit the most when there's more competition. Having more carriers leads to more competition and gives consumers lower prices and better service -- it's simple economics.