Rapidly depreciating property prices in Australia's two largest cities have sparked concerns that consumer confidence could take a big hit in 2019 as debt-laden households and property investors are forced to rein in spending.The latest Core Logic data published on Monday confirms that the slide in housing prices across Sydney and Melbourne accelerated in November, with dwelling prices falling by 1.4 per cent and 1 per cent, respectively.The November data means that Sydney house values have fallen by an average of 8.1 per cent in the last 12 months, while in Melbourne the annual decline is 5.8 per cent.The Core Logic figures comes as several leading banking analysts have begun forecasting sharp rises in non-performing mortgages in the next three years.In an alarming report on the prospects for the Australian home lenders, Deutsche's banking analyst Matthew Wilson likens conditions prevailing in the local housing market to those that precipitated the Irish property crisis a decade ago.Irish house prices declined by 60 per cent in 12 months in 2008, despite low interest rates and benign levels of unemployment.That property market collapse crunched household spending and caused non-performing mortgages across the Irish banking system to blow out to 25 per cent.Wilson is not expecting the Australian property correction to be as devastating, but he leans to the view that it could get very ugly."At best, mortgage growth will continue to slow as deleveraging works its way through the economy constraining house prices and discretionary spend, but it's unlikely to be beautiful," he told clients in research report last week."At worst, we confront the Irish-like scenario. "However, we think it's unlikely to reach the Irish heights of 25 per cent housing NPLs for a decade due to a more independent policy infrastructure. "However, a zombie-like mortgage book is possible. "It is not politically palatable nor logistically easy to foreclose on vast amounts of troubled mortgages. "Capital therefore may not be immediately available to deploy into productive recovery credit."Wilson's pessimistic outlook might be supported by recent qualitative research that points to a dampening of confidence among Australian households.A survey of 1500 mortgage borrowers by ME Bank confirms that home buyers who purchased in the past three years are the most worried by recent falls in house prices, particularly in Sydney and Melbourne.Around two-thirds of borrowers who bought into the property market in since 2015 say they are worried about the falls in house values and that it could have implications for their spending over the next 12 months.The survey found that 73 per cent of respondents were planning to "be more careful with their money" as a result of the correcting market.The steepest annual declines in NSW have occurred in Ryde (down 12.1 per cent) and Baulkham Hills (down 11.3 per cent).Melbourne's inner eastern suburbs such as Kew, Hawthorn and Camberwell are among the hardest hit property markets in Victoria, having posted average declines of almost 12 per cent this year.While Melbourne and Sydney account for more than half of the country's residential property,