Citigroup has forecast that fintechs' share of "the consumer banking wallet" in North America and Europe will grow from the current level of around one per cent to ten per cent by 2020 and 17 per cent by 2023.Citi's Global Perspectives & Solutions unit has released a report on digital disruption saying the Chinese market, where companies such as Alipay and Tencent have as many clients as the top banks, offers a view of the near future.According to Citi, China has the biggest P2P lending market in the world, accounting for about three per cent to total consumer lending. P2P lending share in the US is estimated to be 0.7 per cent.Citi said the driver of change was not the technology but the change in consumer behaviour. Smartphones have revolutionised content delivery and new financial service offerings can win new clients with "a better experience".Seventy per cent of fintech investments to date have been in the personal and SME segments, in payments and lending.Evidence that fintechs and changed consumer behaviour are having an impact can be seen in the growing number of bank branch closures. Citi said branch numbers in Europe and the US could drop by 30 per cent to 50 per cent over the next few years.But Citi also has a warning for fintechs. It said business models based on a lower cost-to-serve may be relatively easy for incumbents to replicate."Companies that are solving a financial need in a different way rather than simply a cheaper way are more likely to maintain their innovative edge for longer," it said.It also said digital segments were significantly more concentrated that traditional segments, suggesting that a shakeout was ahead for many fintech hopefuls and not just uncompetitive incumbents.