This is fact. Not only is the space undergoing continuous change, it is very new. 

"Many financial institutions still don't offer their own apps," said Jose Resendiz, a spokesman for Digital Insight, which he said presently services around 500 mobile banking clients, of which half are credit unions.

That means many credit unions must launch a mobile app, and also consider offering what is emerging as the new must-have, mobile remote deposit capture.

Read more: Decoupling mobile from online banking …

Beyond that, Resendiz said Digital Insight is currently pushing to decouple mobile banking from online. In most deployments, mobile is parasitic on online banking and cannot stand alone. 

But lately, Resendiz said a clear trend is the growing number of mobile-first consumers, who may sign up with online banking but never return to that channel. As a result, Digital Insight plans to roll out a mobile-only solution by this fall, he said.

Most experts expect mobile-first strategies will percolate into many financial institutions this year. That may be a big change internally, but it is not likely to be one that consumers notice because it happens under the hood.

Another reality: experts said that credit unions have to continually upgrade their apps to stay competitive as consumers clamor for more functionality in all of their smartphone apps.

Elaborated Atlanta-based mobile banking expert David Eads of Mobile Strategy Partners, "Many credit unions have 15% of members using mobile now and they think that is good enough. It isn't. Many big banks now are at 37% and climbing. Credit unions, to remain competitive, need to be approaching 50% usage this year."

That means credit unions have to work hard to increase the appeal and usability of their apps. 

Yet a kind of simplicity is baked into every mobile banking app by virtue of the fact of the small screen, said Gary Ambrosino, a mobile apps expert and president at TimeTrade, which sells scheduling software to many financial institutions. 

"There is a limit to how complex a task can be on a small screen. It is too easy to lose users.  That's a hold up when it comes to introducing new features on the mobile device," he said.

In other words, it is easy to look at online banking sites on a 30-inch monitor and wish that all those features were accessible via mobile; but for now, the constrained reality is smaller, and that is not likely to change soon.

Read more: New credit union features in 2014 …

So, what are leading edge credit unions cooking up now for mobile?

Know that many credit unions plan to roll out key, new features this year.

The tools industry executives presently talk about adding will not be dramatic – there is no Mobile Remote Deposit Capture "must have' feature in the list – but they will, hope these executives, increase the convenience and utility of the mobile app.

Out of that may also come more users.

A case in point: Navy Federal is introducing a capability it calls "PIN and In," said Gound. That means logins via the mobile banking app now can be done just by entering a four digit PIN, which is much easier than typing long passwords on a glass screen. 

"We believe it is very secure and also very convenient for members," she said.

That may seem insignificant, but if it results in more member engagement, the payoff is real, Gound said.

She added that at Navy Federal, many new capabilities are under review, including offering credit card and auto loan applications via mobile. The institution is also looking at biometric authentication, such as fingerprints. However, it is not ready to roll out such innovations, not yet.

At $5 billion Digital Credit Union in Marlborough, Mass, Vice President for Support Services Julie Moran said the institution plans to soon roll out a feature that will let members swipe within the credit union app to see their account balances. 

"You won't have to log in," said Moran.

That puts DCU alongside Randolph Brooks Federal Credit, a $5.6 billion Live Oak, Tex.-based institution, which last fall released a widget that lets members who opt in see a self-refreshing balance with no login required. 

The $4.1 billion Pennsylvania State Employees Credit Union in Harrisburg, Pa. makes three credit unions offering that option, said Christopher Owens, mobile product manager. PSECU will release a widget this year that will let members see their balances.

"It's very convenient and we know members will like it," he said.

Also in the works at PSECU is a new person-to-person payment service, powered by PayPal, that will let any PSECU member send funds to a third party, PSECU member or not, although they will need to sign up with PayPal to receive the money, Owens said.

He indicated that PSECU had been looking for a way to offer p2p for some time, and between the ease of use of the PayPal tools and that company's sizable brand recognition, PSECU decided to go with them. 

Another PayPal plus: "The money transfer is essentially real time," said Owens. "You can be at a swap meet, agree on a price with a seller, and send over $20 in real time to complete the purchase. Our members had told us they wanted this kind of capability."

All these changes sound tiny? Indeed.

But they will add utility for members.

That, said the experts, is what mobile banking app development presently is about: Introducing small features that add incremental benefits that members can enjoy immediately, with little or no learning curve.