Over the long term, the historic and average price difference...

Over the long term, the historic and average price difference (in percentage terms) between Australian capital cities-and indeed between Australian capital cities and Australian regional cities-will continue to remain relatively consistent.

So if you agree with the above premise then you must also agree with the following conclusion: At some point, prices in Sydney/Melbourne will fall/stagnate and prices in Brisbane/Adelaide will rise to the extent that prices between the cities will again reflect the historic and average price difference. In precisely which year will the above occur? No one can answer that question, unequivocally.

But those that argue the current (widened) price difference (in percentage terms) between the capital cities is some sort of new miraculous trend that will continue unabated will be somewhat disillusioned overt the long term.