Does your city have enough freaks in?

Brad has a background in economic geography. I am trying to buy an appartment. The two are more linked than you might think. We got talking about cities and urban planning.

Brad told me that a city needs 200,000 - 300,000 people. People come to cities for the work opportunities and the lifestyle diversity. You can be a freak in way you can't in a town of 30,000 people*. And Richard Florida would say that cities need freaks to make them economically useful.

However we both discussed Sydney getting too big. It sprawls out to the Blue Mountains, down to Wollongong and up the Central Coast. And my suspicion is that its more like California than London in that travel is multi-nodal (people living in Strathfield commuting to Chatswood) rather than the majority commuting to a comparatively large CBD**. Assuming that transport costs will rise over the coming decades, this will become more and more of a problem. To what extent will Sydney fracture? Will the emerging megacities swell and then break apart under their own weight?

*like the one I grew up in, not that I'm a freak, er...
**Happy to hear from an urban planner that I talking codswallop here.