I agree that the time's ripe for DT to do something. But it's hard to tell what that something may be.
Sprint's a bad fit. Clearwire makes more sense but is owned 51% by Sprint and that will either A) setup a merger with sprint down the road when DT and Sprint share a 4G platform thanks to their shared ownership or Clearwire or B) will make for an uneasy marriage a la Vodafone+Verizon=VZW.
AT&T is too big as it is so regulators aren't going to allow another competition-reducing merger that involves it.
Some of the smaller/regional carriers like USCellular, Cricket, MetroPCS et al...I don't see the point aside from bulking up subscriber numbers for an eventual sale to a bigger fish...but A) There are no bigger fish looking/able to buy and B) I thought DT wanted to remain a player in the US market.
The only viable option may be for DT to go it alone. Which means lots of capital expenditure and winning customers the old fashioned way. Not sure if investors will be that patient.
DT could also partner-up with or sell to another overseas player. Vodafone/Verizon are both rumored to be interested in exiting their partnership. Maybe Vodafone would want to enter the US on its own? SK Telecom? An Indian or Chinese provider?
No easy options. The market is saturated and the economy sucks. Tough time to make big moves.