"Apart from mergers, carriers may also choose to preserve profit margins by sacrificing market share, losing the lower value consumers and keeping those who choose an operator not on price but for network quality, added value services or choice of devices, for example."
Well, the problem is (as you really did cover in the same page of the article), AT&T and Verizon Wireless already do this. Damn are they expensive! But, network-wise they absolutely clean Sprint's and T-Mobile's clocks, VZW has the most coverage but both VZW and AT&T have enormously more coverage than Sprint or T-Mobile.
T-Mobile, they have very fast network in a very limited area and way the hell too much EDGE* everywhere else (which they are in the process of upgrading directly to LTE, since 3G is already obsolete.) *This is a bigger deal than you might think, EDGE in the US isn't getting that 100-200kbps data speed you might see on European EDGE, it's usually like 0-5kbps (1/10th dialup speed, so even GMail etc. will simply time out.)
Sprint... well, they do have loads of spectrum, but the execution? Heh. Typically, they'll 1) Release grandiose 3 or 4 year upgrade plan that'd result in a good to excellent network (depending on the market.) 2) When the first year's up, it seems they've gotten through like 2 months of planned upgrades. 3) Delay delay delay... 4) After 4 or 5 years, they'll be through the originally first year or so of upgrades, and the rest is scrapped since they are on the *next* round of upgrades by then. I do hope they do their upgrades this time, and with Softbank's cash maybe they will.
Two other points:
First, LTE. MetroPCS *did* acutally roll out LTE and the world's first VoLTE deployment, in order to provide 1-2mbps data and voice at lower costs than their existing CDMA network, then passed some of those savings on through lower monthly bills. However, the other carriers viewed LTE as this magic cash cow and thought (at least at first) that they'd be able to charge all this extra money for the service, whereas (most) customers see it as the carriers problem to maintain a reasonably fast service and don't care if it's 3G or 4G as long as they do so. I must agree, if there were a "4G surcharge", I'd happily accept ~1mbps or so EVDO service and pocket the surcharge. (There are the other customers, as seen on howardforums, who love to see just how high a speedtest they can get, whether they "need" the speed or not.)
Second, AT&T *loves* to conflate wireless, wireline, and cable figures. (Well, now that I Google it appears Verizon now also does this.) Last figure I saw for Verizon Wireless alone was (a few years ago) like $5 billion, and AT&T Mobility was like $4 billion (with both planning to bump it up as high as maybe $8 billion a year in the fastest -- i.e. most expensive -- portion of the LTE upgrades.)