We are talking about infrastructure here, complete
4G deployment take huge amount of investment that smaller
players just can't afford to do right. Instead of having
Tmobile and Sprint deploy totally separate base stations
and/or upgrades, might as well do it right with the
bigger guys. Otherwise, consumer might end up dealing with
spotty coverage, shitty speed with the smaller guys, or
having to foot the bill for renting ATT's network.