It is business as usual for T-Mobile. They keep on selling 4G phones. They even have the girl from the picture above making fun of AT&T's network in recent commercials.
Did we forget that AT&T bought out T-Mobile USA? Did we forget that AT&T said they were going to raid T-Mobile's towers for its upcoming LTE 4G network. Let us also not forget that T-Mobile and AT&T do not have compatible 3G and 4G, so if you buy a new T-Mobile phone now, it most likely will not work in three years for 3G or 4G speeds. The phone might not even make it to two years. So if you are thinking about buying a new T-Mobile phone, DON'T!
And why does AT&T not have an LTE 4G network, like the one Verizon has? AT&T was racking in profits with the help of iPhone for the last years. Perhaps AT&T's priorities are in buying out companies rather than building up its network. Though I dislike to admit it, buying out your competitors is a winning strategy for gaining new customers.