How would banks make money if banking products or services were free?

My response to this discussion is

Banks are going through what Telco's have gone through in last decade. That is, that their core product voice (analogue) is digitised and hence voice based service is free in competitive markets. In case of banks money is still not fully digital, but its not that far either, it will be digitised in few years. In that case then banks or telcos become digital platform for transaction enablement, like Google is for search. And so downstream consumers get free services and upstream consumers pay for interacting/engaging with downstream consumers using the digital platform and in that case it will be banking's core platform. Not only banks but any industry where core offering can be digitised as a multisided platform will have to be adopted else the business will go belly up. Media is evolving on those same lines.  In case of Australia its bit hard because markets across verticals are either monopoly or duopoly, its not a competitive market as compared to US/Europe. Having said that internet and internet of things will force it and banking will have to adopt that model else they risk of losing out to others.  That means services on downstream might not be totally free but some will be for sure. If Australia was more competitive and less regulation then downstream services will be totally free. Other thing about digital based model is that Marginal Cost (MC) is nearly negligible when it has to expand the business, where as in a brick and mortar/non digital based business Profits become maximum when MC = Marginal Rev. Digital business doesn't suffer from this economics.