Most of my friends want to live in certain areas (usually close to the city) for the lifestyle, to be close to family, because that's where they grew up, etc. This is a human trait that's not likely to go away. A friend asked me why I want a house in the Hills when, for the same price, I could get a nice townhouse 15 minutes from the city. Less space, but a much shorter commute, more nightlife, etc.
Given that, does anyone see a mass migration out to country areas so that you can, for example, get a house instead of living closer to the city but in a unit? People aren't even willing to move to Western sydney to live in a house. Hence why those areas are falling in price while the North Shore, for example, is going up.
For the price of a 2 bed unit on the Lower North Shore I can get a pretty nice house on a big block of land out west. Yet Western Sydney prices are falling. Why? Because people aren't willing (for now) go live out there. And we expect them to move into a regional town instead?
What's more likely is that bit by bit they resign themselves to smaller accomodation. So every year young people who move out get smaller and smaller places, further and further out, until the whole of central sydney is filled with units. New units aimed at the starter market will become smaller and smaller. Conversely older (bigger) units will become more valuable because new units are smaller, and the old suburban block is even more valuable because you can build a block on it.
Think that's far fetched? Look at old photos of Hong Kong, or Tokyo, or Manhattan. I'm sure none of the people back then could have imagined just how much you can build on a scrap of land. I went to the Museum of New York earlier this year, and they had a video of how Manhattan spread from the Southern tip up to Harlem. Incredibly interesting and instructive.
Alex