In an interview, Meara explained that most financial institutions haven't yet explored reducing branch operating costs. Until they do, the mobile cost savings are largely fictional.

“If you don't change the costs of infrastructure you are adding costs with mobile,” he said.

Credit union leaders in mobile banking said two things are clear: mobile banking today is a necessity; and, little by little, genuine savings are emerging that may help institutions better control costs going forward.

Each institution's story is different, in fundamental ways, but collectively they depict the shape of the mobile journey for just about every credit union.

John Worthington, executive vice president at the $7.3 billion Security Service Federal Credit Union in San Antonio, said, “If you don't have mobile banking options today, you are at a competitive disadvantage in the financial services marketplace and could lose members to other institutions that do.”

However, he added that it is too early to tell how much savings mobile services will bring the credit union. Security Service debuted its mobile banking app in January 2013 and, Worthington said, “intuitively we know it is a lot less expensive to serve a mobile customer than for that person to come into a branch.”

The $14.4 million Dupage County Employees Credit Union in Wheaton, Ill., tells a different story.

Amy Brandt, vice president of business solutions, said that earlier this year “we closed a branch in a neighboring county. It did not get much traffic. Mobile lets those members stay with us, and we haven't lost many.”

Like Worthington, Brandt said it's too early for Dupage to state how much two years of mobile banking has saved the credit union in operational costs. However, she added that Dupage does know it costs much less to process a check using mobile deposit compared to a teller line.

She said she guessed mobile banking costs as much as 40 cents per check, while the teller line the cost might hit $4.00.

Brandt added that Dupage has lately detected a decline in traffic on its online banking channel, and the credit union assumes those members are transitioning to mobile banks, as mobile usage continues to increase.

“We believe that members will continue to use mobile more,” she said. “Our branches will be repositioned. Can we do what we need in a smaller space? We are beginning to ask that question.”

At the Marlborough, Mass.-based Digital Credit Union, Vice President of Support Services Julie Moran said although no one in senior management is specifically asking about the return on investment of mobile, the $5 billion Digital is realizing cost benefits.

She pointed to a number of indicators. Notably, mobile deposit has outpaced mailed deposits for several years, and those mobile transactions are significantly cheaper to process.

DCU also has noted a significant drop in deposits through the shared branching network, which is very expensive, she said.

In recent years, DCU has closed two branches, in Alpharetta, Ga., and Colorado Springs, Colo.

“The majority of members in those regions stayed with DCU. Mobile lets that happen,” she said. “It won't be like the past, where every town had to have a branch. Many members can serve themselves over mobile.”

In the long run, she added, mobile services will let the credit union operate more efficiently.

The story at Rivermark Community Credit Union, a $570 million institution in Beaverton, Ore., comes down to the dramatic success of mobile remote deposit capture, said David Noble, marketing leader.

He said the institution introduced MRDC 18 months ago and already 18% of deposited checks come in through that channel.

The credit union's 21,000 mobile deposit users have deposited some $95 million during that time, and he said members are coming into branches less frequently.

“Member behavior is changing, and we are looking at our branch network to make sure it best serves member needs,” he said. “It's safe to say there are substantial savings that come to us through the use of mobile, but we would like to know more about the cost analysis.”

The $4.1 billion Pennsylvania State Employees Credit Union in Harrisburg, Pa., tells an entirely different story. Despite its size, ranking comfortably among the top 25 credit unions in the country, PSECU has only one branch.

“We are effectively a branchless institution,” said Owens, who added that PSECU has had a lone service center in Harrisburg for decades. “If it wasn't for mobile there would be pressure to open branches. We haven't had the expense of building branches.”

And, he said, this has allowed the credit union to compete successfully against other financial institutions.