House prices are going down in Sydney, Melbourne and Hobart...

House prices are going down in Sydney, Melbourne and Hobart because the prices overshot on the way up, just like they did during the previous cycle (peaked in 1989).

Prices in Perth still rising due to the mining boom and the later start in the cycle.

Against time tested measures of:
1. average house price to average household income;
2. rental yield;

house prices went too high. The adjustment will probably be slow, depending on future interest rate levels and unemployment rates. Doubt that there will be any capital growth, after inflation, over the next few years.