What a load of crap...
America's underdog T-Mo hooking up with America's shittiest carrier Sprint? T-Mo is a pure GSM network while Sprint is CDMA, so until & unless you go to the 4G tech & beyond the two networks can't even talk to each other. You certainly can't take a Sprint phone & switch it to T-Mo's network or vice versa, not unless it's a pure 4G device.
TFA is correct in mentioning that the regulators have stomped on this idea every time before, the loss of competition is just too big of a deal to set aside. America only has four big carriers in the field, reducing it by consolodating two of them so there would only be three? That's not competition, that's the exact opposite of it. We need MORE players on the field not fewer.
I wish America were more like you on the other side of the Pond in this one - all one carrier tech (GSM) so the carriers had to actually compete to get our business, device makers had to make devices that worked with any carrier so the customer could use it anywhere, and switching devices/carriers was as easy as swapping a SIM card. You lucky bastards. =-Jp