Current that never a problem for a bank. If you walk away, the...

Current that never a problem for a bank. If you walk away, the bank just sell the property for a profit.

With a high percentage of low doc loan (interest only loan) which the regulator has recently flagged as problem area, the loan will never repay in a single generation. Sooner or later, the bank has to act.
Once the property prices spiral down, the bank will panic and they have to take action. Although Australia law has a recourse clause - virtually you cannot declare bankruptcy on property - people will have to decide, either to continue paying interest with no chance of owing the property or just run away and wait for the bank to get them.