On Monday, John Legere leads the quarterly AT&T (T) and Verizon (VZ) bashing session known as the T-Mobile USA (TMUS) earnings call.

The T-Mobile USA CEO took shots at Verizon on Tuesday after the carrier announced that it had lost 289,000 post-paid phone subscriptions in the first quarter despite introducing an unlimited plan, and Legere is sure to harp on the carriers' misfortune during the call.

In addition to an update on the state of wireless competition, investors will listen closely for any signals about a potential merger of T-Mobile USA and Sprint, which has long been expected.

Aggressive customer offers from T-Mobile and Sprint have created the competitive pressure that caused Verizon's first-quarter subscriber losses and prodded the carrier to finally go unlimited. AT&T will provide its own quarterly numbers on Tuesday.

Combining Sprint and T-Mobile would theoretically lessen the pressure on Verizon and other carriers. But while some of the aggressive phone deals could be a thing of the past in a market with fewer service providers, analysts suggest that unlimited plans are here to stay.

"Consolidation, particularly a move from four to three operators, has been shown to reduce competitive intensity significantly," Seth Wallis-Jones, Senior Analyst with IHS Markit Technology said in an email. European regulators recently rejected the U.K. merger of CK Hutchison Three and Telefonica O2 on the grounds that consumers would have less choice and pay more, while innovation could suffer, he noted.

In Canada, where the Big Three telecoms BCE (BCE) , Rogers (RCI) and Telus (TU) dominate wireless, telecoms enjoy higher valuations than their peers south of the border. "If the U.S. market was to evolve in a similar manner post consolidation, we could see increased pricing power accrue to the carriers," Barclays analyst Amir Rozwadowski wrote in a recent report about the potential for wireless consolidation. Canadian telecoms trade at 8 to 8.5 times Ebitda, he noted, while AT&T and Verizon both trade at less 6.8 times projected 2017 Ebitda.

Even in a market with three carriers, however, Recon Analytics founder Roger Entner suggests that leaders Verizon and AT&T may not catch a break.  

"If you continue to have a hell-raiser like Legere running the combined entity, you will continue to have massive competitive drivers," Entner said.

Editors' pick: Originally published April 21.

Even a poorly-executed merger of Sprint and T-Mobile, Entner argues, would not necessarily yield market tranquility. "Then competition goes even higher because somebody is drowning and when someone is drowning, they flail around," Entner suggested. "They make short-term rational -- but long-term irrational--choices, like 50% off," referring to a Sprint deal that let customers pay half of what their bill with their old carrier. 

So what happens to phone promos and unlimited plans if Sprint and T-Mobile, which have been shaking up the wireless market, become one?

The carriers would likely cut back on phone deals on flagship devices like the Apple (AAPL) iPhone and Samsung (SSNLF) Galaxy. "Promos such as Sprint's latest two-for-one offer on the Samsung S8 have managed to staunch subscriber losses, but with [Sprint's] quarterly losses of $479 million, the indications are they are not sustainable," Wallis-Jones of IHS Markit said. 

Unlimited plans are another matter, however.

All four carriers have started signing up customers for all-you-can-eat data plans, so poaching subscribers from a rival without a competitive offer will become difficult. "Once you go unlimited," Macquarie analyst Amy Yong said, "you can't go back."

Unlimited plans can work financially as long as the carriers can get a handle on video usage today and in the coming years, Entner said.

Standard definition and high definition video requires about one megabit per second (Mbps) and 5 Mbps, respectively, while 4k, or ultra-high definition video, requires about 25 Mbps. While streaming ultra-high definition video may be beyond the needs of most users, phones such as the Sony Xperia Z5 Premium come with 4k screens. If carriers can predict how much video their customers will watch, they can set their prices accordingly. 

Carriers would have to factor in quality of video that subscribers could stream, and the required network capacity, as part of unlimited plans.

"You can't do unlimited data on 4k. The economics of the current networks collapses," he said. "At 1 megabit per second and 5 megabits per second, yes [the economics work]. That's why that video quality issue is so big from an economics perspective."

Another factor, he suggested, is that people will splurge for an all-you-can-eat offer. "If you give somebody a 20-gig plan and the unlimited plan is $10 or $20 more, many people will take the unlimited plan even if they don't need it," Enter said.

Consumers will expect unlimited plans, even if the wireless industry consolidates. The economics should work as well.

"Unlimited is here to stay," Entner said.

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