Well you see the problem with your argument Codegerm is that what you posted was news well over a year old, whereas the current news as of december is that Sprint is trying to buy the other half of Clearwire. If Sprint owns all the WiMAX then they don't necessarily have to make a decision that jeopardizes pre-existing contracts (i.e. current Sprint 4G contracts, as well as those renewed by WiMAX phone owners who opt not to replace their handsets for any reason), because that would be rather expensive for them, wouldn't it? Sprint knows their customers don't really want contracts; the level of off-contract competition to genuine Sprint service is very high (no pun intended).
If Sprint is willing to pay billions to buy all the WiMAX then I don't see them discontinuing service early. Even if they do decide to cancel WiMAX in 2015, that's still plenty of time to develop 4G LTE modems for existing WiMAX phones. Sprint better take care of their customers, the real question is what exactly is Boost going to do? The official answer I was given by a Boost Mobile Human is that WiMAX service is not getting turned off.