If we had a massive drop in house prices aussie wide, enough to generate negative asset holdings for the average mum and dad, and investor I should add; then no, the banks wont go calling in loans.
If your paying the loan, at the very least interest only then all will be just fine. In fact the banks want you to pay interest forever and never pay off your loan :)
Milesg if the banks did that, as I've said before we'll all be living off PAL and baked beans; Loan or Not
