So the engagement between Sprint and T-Mobile USA is off again, and until the next time they dance around one another, Sprint is focusing on the cablecos. It will be supporting an MVNO-based mobile launch by Altice, even as rumors swirl that its owner, Softbank, will seek an alternative merger plan, with Altice’s rival Charter Communications (whose own MVNO is powered by Verizon). The proposed merger would have created a powerful third player of a similar size to AT&T and Verizon, assuming antitrust authorities could be assuaged, which was considered more likely under the current administration than when Masayoshi Son, Softbank’s chairman, previously went after T-Mobile during the Obama government. Then, he backed away in the face of almost certain…