Other carriers, Leap Wireless, Cricket, ... seem to want Tmo's assets, and ... AT&T had offered to sell it to them. http://www.mobileburn.com/17966/news/att-reportedly-having-d...

But if AT&T doesn't buy Tmo, one of these might merge instead with Tmo or buy those assets directly.

At other times, there has been speculation (or even work done) on a Sprint / Tmo merger which would bring two weak players together but also allow for more direct competition between the GSM and CDMA world with an LTE path going forward.