Executive general manager Adam Bennett made the claim at an event in Sydney today, according to the Financial Review, adding that "if you look at it through the lens of interactions, digital is already on top because some people will look at their bank balance three or four times a day."

Although Bennett predicts that cash could become the exception as customers transact "more and more by bumping, waving, tapping and swiping their smartphones", he insists that branches are here to stay for people who want face-to-face interaction.

The value of branch networks has also been highlighted by numerous technical glitches at NAB and other Aussie banks over the last couple of years. Less than six months ago NAB customers were locked out of their online accounts for more than five hours because of a network failure.

At the same conference, Bennett revealed that NAB is looking into a bring-your-own-device (BYOD) policy for staff, with trials involving 200 top executives and iPads already underway, reports ZDNet.

The bank is working with Telstra and IBM on the initiative, which Bennett admits poses big problems such as how to assign budget for upgrades, technical support for personal devices on the corporate network, and productivity concerns.