The PwC report said banks could significantly boost their bottom lines by going digital putting the cost of the average branch transaction at US$4 ($5.50) each while online and mobile transactions cost between US9c and US19c each.
Symons said the US environment was very different to New Zealand, but proportionally the cost savings here could be similar.
PwC's report puts the banks into three categories - those who put a digital channel on to their front, those who integrate it into their bank-end systems and those who build with a digital mind-set from the beginning.
Symons said: "New Zealand banks are in the first category - they have a digital front end."
But they were increasingly moving into the second category.
Having a digital front end means a consumer can apply for something online via their mobile or desktop but then it takes two to three days for the bank to come back via email or to make any changes.
The next big step is to have a far greater proportion of products and services fully digital from the application process right through - making it easier and faster.
"Some of the banks are moving into that horizon for some products."
Symons said those who didn't change left a lot of opportunity for disrupters to come into the market and could also see costs rise as they had to staff a front end digital system while managing their legacy systems.
"Thirdly - they start to lose relevance to customers - who will move from a broad relationship with their bank to using a range of different platforms."
Symons said banks needed to make a cultural shift in the way they thought about technology.
"It's not about buying technology or talent but shifting the culture into a digital mindset."
That was about focusing on customer experience and getting good data which enabled analysis.
The data could then be used to make good decisions about products and services including co-designing products with customers.
Going digital also made it far quicker to get new products and services out versus the old system of spending millions and taking a long time to design a revamp.
Symons said he expected banks to shift their culture in the next five to 10 years.
"Our banks are looking much more like a digital end to end organisation."
He said it started with having a quality digital core because good underlying technology enabled good customer information to be gathered.
"Without that it is hard to build a cohesive strategy."
"Banks will need to be very clear about what they want to look like."