T-Mobile USA and Sprint have finally got the go-ahead from the US authorities for their $6.3bn merger, which will create a stronger counterweight to AT&T and Verizon, while ushering in a potentially disruptive fourth MNO. The concession which the two MNOs made to the FCC and Department of Justice – which were concerned about the reduced competition if national MNOs were reduced from four to three – was to divest some spectrum and customers, and offer favorable MVNO terms, to Dish Network. There were many rumors last month that Dish would be supported by a large web player like Google or Amazon in the much-anticipated deal with ‘the new T-Mobile’, but in the end, the company went alone. That will…