Analysts say the banking sector's dominance in funding mortgages and business loans will come under increasing pressure over time.
Research in Australia suggests banks there will be tested by stricter rules and increased competition from growing superannuation schemes.
The study, by the Australian Centre for Financial Studies, found the capacity of the banks to fund the economy will be curbed by limits on borrowing overseas, the shift of savings from bank deposits into superannuation schemes, and the greater involvement of investment funds to act as lenders.
New Zealand's $16 billion super pool is tiny in comparison Australia's approximately $1.5 trillion.
However the head of financial services at KPMG, John Kensington, says some of the same trends are evident here, with people's gross income diverted into KiwiSaver.
Mr Kensington says growing KiwiSaver funds are likely to move into areas traditionally funded by banks as they look for new opportunities to invest, but it will be a gradual shift over the next decade. However he says banks have proved adept at responding to challenges in the past.
In New Zealand, the banking sector makes up four-fifths of the $500 billion plus financial sector. About a third of the banking sector's funding needs come from overseas.
The director of the Centre for Financial Services and Markets at Massey University, David Tripe, says new rules to make the financial system safer by forcing banks to hold more money will make them less profitable.
Technology is also making it possible to bring lenders and borrowers together more cheaply than banks can provide, though that market is still in its infancy.
But the banks are themselves sizeable KiwiSaver providers, and have moved into wealth management, where they act as a one-stop shop for all their customers' financial needs.
Bankers' Association chief executive of the Kirk Hope says lending to would-be home buyers and smaller firms is likely to remain the preserve of banks.
Nevertheless, he admits banks are facing new challenges, and they're unlikely to have it all their own way in the future.