There's been a lot of griping about AT&T's $39 billion acquisition of T-Mobile USA, and for good reason. The deal will give AT&T and Verizon Wireless a near-duopoly hold on the U.S. wireless market; make it more difficult for smaller carriers – especially Sprint – to compete; and has raised fears that the merger may limit choice and raise prices for consumers.

Concerns over the implications of the merger, voiced by everyone from Sprint to state Attorney Generals, have cast a shadow over the deal.

But couldn't there be a bright side to it?

With every major upheaval in the wireless industry, there are both winners and losers. When AT&T announced in March that it planned to buy T-Mobile, the losers seemed obvious: any carrier smaller than Verizon Wireless.

Some say that this may not be the case.

Mark Beccue, an analyst at ABI Research, says that smaller carriers may be in a good position to land defectors from T-Mobile USA's "value segment"  – lower ARPU customers using feature phones who are less profitable than the carrier's smartphone subscribers.

"I don't think T-Mobile customers are going to find the right kind of pricing from AT&T," Beccue says. "Every indication is that AT&T wants this deal for capacity and the growth of their network – I don't think they'll change their philosophy in pricing."

Under Beccue's hypothetical scenario, the merger could present a window of opportunity for carriers like Sprint, MetroPCS and Cricket to attract T-Mobile customers shaken by the deal.

For much of its existence, T-Mobile positioned itself as the low-cost alternative to AT&T and Verizon Wireless. T-Mobile customers pay less for unlimited talk, text and data than subscribers on comparable plans from Verizon Wireless and AT&T.

Though the company has expanded significantly into smartphones, its core base of value-oriented customers - those of its 7 million prepaid customers and the estimated 18 million contract customers not using smartphones - may be turned off by the thought of paying more for their wireless service.

This could open up a chance for carriers like Sprint, MetroPCS and Cricket to bring new customers on board – a bright spot in an increasingly bleak competitive environment.

"I don't necessarily see this as a bad thing," Beccue says. "It's going to make AT&T stronger, and all AT&T customers benefit. It also gives some other players like MetroPCS a pretty decent opportunity to grow because of this T-Mobile issue."

It's too early to say for certain how AT&T will handle this segment of consumers. The operator could sell them off in government-mandated divestitures, try to upgrade them to smartphones, or create a new sub-brand specifically tailored to T-Mobile's low-ARPU customers – a tactic that would be at odds with AT&T's historic focus on full-service offerings.

AT&T declined to comment on its post-merger plans, and T-Mobile could only provide limited detail on how it planned to deal with customers once its merger with AT&T is approved.

The company said in an e-mail that "all customer contracts entered into before the change of ownership will be honored [for their applicable period]," but could not confirm that customers would be able to keep their old T-Mobile plans once their contracts ran out post-merger.

That leaves open the possibility that subscribers would have to switch to AT&T's plans, which tend to cost more than comparable offers from T-Mobile.

A possible result of this: churn. T-Mobile's lower-ARPU customers may defect to carriers offering service cheaper than AT&T's if AT&T doesn't make a concerted effort to retain them.

Beccue estimates that AT&T may see more than a fifth of T-Mobile's customers switch to other providers if it doesn't offer those cost-conscious customers cheaper wireless plans.

Informa Telecoms & Media analyst Mike Roberts agrees with Beccue's general assessment of the situation.

"AT&T has already been talking about bringing up T-Mobile's ARPU to their levels – that means prices will eventually go up," Roberts says. "There will be some people firmly in T-Mobile's value segment that would go to some of the players like MetroPCS, Boost or Cricket if their prices go up."

He expects that AT&T will make an effort to retain T-Mobile's more valuable smartphone customers, but may decide to provide fewer incentives for subscribers looking to get a good deal.

Roberts cautions that this will depend on how the deal plays out, but thinks some level of defections is likely.

Of course, this is all speculation - AT&T's acquisition of T-Mobile is at least a year away from closing – and not everyone agrees with the assumption that T-Mobile's low-ARPU subscribers aren't valuable to AT&T.

Dan Hays, a director at management consulting firm PRTM, isn't so sure that AT&T will let T-Mobile's subscribers slip through their fingers, even the less profitable ones.

"AT&T is paying a king's ransom on a per-subscriber basis for T-Mobile, so to give up that installed base would not make sense," Hays says, pointing to the carriers' aggressive efforts to put out a positive message to their subscribers.

Both AT&T and T-Mobile have already launched outreach efforts on Facebook and Twitter, and have also created their own websites to answer subscribers' questions about the deal and alleviate concerns about how the merger will affect their service and devices. The companies are presenting a unified front to both their subscribers and the media. Their message: This merger will give you better service.

AT&T's stock purchase agreement with Deutsche Telekom indicates that the company is willing to accept up to $7.8 billion in "adverse effects" – divestitures of spectrum, network assets and subscribers – to get the deal approved.

That could mean selling off a significant chunk of T-Mobile's subscriber base, but there's no guarantee those assets won't end up with Verizon Wireless instead of with the likes of Sprint, MetroPCS and Cricket.

Sprint hasn't indicated it sees much of an upside to AT&T's buyout of T-Mobile. The company has issued multiple statements opposing the deal and has asked regulators to look into the merger. For its part, MetroPCS has had a more optimistic response to the merger. Company COO Tom Keys told Wireless Week at CTIA that the deal has "taken out a competitor in the industry, a competitor that mirrors our value segment."

Shakeup Likely for Vendors, OEMs

AT&T's competitors aren't the only ones affected by the deal. Big changes are in store for equipment vendors and device manufacturers, as well.

AT&T's incumbent equipment vendors, Alcatel-Lucent and Ericsson, are likely to land contracts to handle the integration of T-Mobile's GSM network. Its IP core network vendors, which include Juniper Networks and Cisco, have been held out as likely favorites for capacity upgrades in AT&T's IP core.

At the same time, the merger has dealt a huge setback to T-Mobile incumbent vendor Nokia Siemens Networks. T-Mobile is Nokia Siemens largest U.S. customer, and its acquisition by AT&T puts Nokia Siemens out of the picture for future network upgrades.

"AT&T's core suppliers are going to benefit the most from this. Anyone who was a core supplier to T-Mobile, their business is going to be under pressure," says Technology Business Research analyst Chris Antlitz.

Antlitz says AT&T's buyout of T-Mobile will make it more difficult for non-incumbent equipment vendors like Huawei and Nokia Siemens to gain ground in the U.S. market.

"The pie is basically shrinking," Antlitz says.

The same applies for handset makers. Even with its dedication to best-in-class smartphones, AT&T is unlikely to bring over every single device in T-Mobile's portfolio.

Instead, AT&T will probably cull some devices while pushing customers to buy other devices. As a result, there will eventually be a smaller variety of devices on the market.

AT&T will also be able to leverage its massive market share to negotiate lower prices from GSM device manufacturers. OEMs will have to churn out more of the same model, at a lower price.  It's not clear so far how this could affect their bottom line.

Obviously, a lot of things still have to play out before stakeholders in the wireless industry will be able to fully grasp the implications of AT&T's buyout of T-Mobile. The merger has wide-ranging implications for carriers, equipment vendors and device manufacturers. Only time will tell how detrimental – and positive – those implications are.