I'd agree entirely that income ratio is important for FHB, because they have a small (20%) deposit.It is one of those strange things in debt deflation that the price of assets declines and debts remain the same. They eventually have to be written off or paid off with wages/earnings. That is why the income ratio is relevant.
However, it's a lot less important for upgraders because they have a big (50%?) deposit. And existing OOs is by far the majority of the market.
According to one survey the Sunshine Coast is the most unaffordable market in the world. It's unaffordable to FHB. However, it's affordable to the demographic that lives there - mostly retirees They don't need to borrow because they've got a 100% deposit that they've saved/invested over 40 yrs, so their income/mortgage servicability ratio is irrelevant.
Maybe studies should take mortgages/LVRs & demographic into account on a suburb basis to give a better picture of whether a suburb is affordable to the demographic it currently houses, rather than just income.
The RBAs measure of affordability uses the median income of the 25-39yo demographic and a 30th percentile house (ie well below median) & IRs. The RBA is well aware that the oft-quoted 3x income ratio no longer works for several reasons - big deposits, relatively low IRs & higher discretionary income being the main ones.
It's in no-ones interest for long term negative or zero capital return. The govt & RBA & banks & existing property owners will do all they can to avoid it. It will lead to the loss of retirement savings, the loss of the wealth effect, the possible failure of the banking system and a deflationary spiral (a la Japan). It's only in the interest of a v. few investors (like you) and FHB - both of which are in a minority.When expected capital return becomes zero or negative, people will have to repay their debt or try to write off the debt.
The 3rd alternative is inflate the value of money (print more $$$), so the debt is inflated away over time. I can't see much debt being written off (except in a few big business basket cases), but I can see repayment of debt and higher inflation.
I can see some Commercial IP falling >50% as the economy stalls & businesses go broke - unlisted property has in the past followed listed property which has already fallen by 40-95%.
I can envisage falls of 50% in some specific circumstances - eg mining towns, top end property.
I can see the bottom end staying flattish - being supported by FHB with FHOG & low IRs.
I'd expect the huge majority of the rest to have lower turnover, and increased distressed sales as unemployment rises. A few sales will bring down the medians.
So I feel the market is likely to compress from the top - a good time to try to upgrade because the next suburb up will be relatively less expensive.
The lower turnover will mean less reliable stats, and the distressed sales will force the median down a little. How long this all goes on for is anyones guess . And anyone who thinks they do know is more likely to be wrong that right IMO.