because its smaller customer base and lack of a 4G offering means it simply won't be able to compete with the three carriers currently in front of it. A Sprint merger has been floated several times in recent memory, and such a deal would make T-Mobile parent Deutsche Telekom a carrier in line with AT&T or Verizon.
First of all, I don't think that lack of 4G offerings is going to be what kills T-Mobile. If anything it is going to be hardware. If T-Mobile doesn't step up and give users a choice of high-end phones that are on-par with phones like the Incredible and the EVO4G in terms of processing power and features overall than people will be forced to go with another carrier. Just look at how many people are flocking to AT&T for the IPhone. The IPhone4 doesn't support 4G.
Also, even if T-Mobile merges with Sprint it doesn't mean that it is going to disappear off the face of the earth.
