Sydney is cancerous, metastasising ever onward. This is not to say that Sydney cannot grow in ways that preserve or even accentuate its advantageous position in the world – just that this is not happening, and that growth is of course serving the crassest commercial imperatives, as you would expect under capitalism.
Recently, we had a property magnate condemning the existence of trees in Sydney, which take up valuable space for construction. Well, try this on for size: 90% of Sydney's perishable vegetables are grown within the metropolitan area.
This accounts for many things. It accounts for the wide variety of ethnically-exotic produce available in Sydney, and the fact that vegetables are often cheapest in smaller stores in ethnically-diverse areas of town.
Sydney is built on top of some of the best arable land in the whole continent and its basin still contains a lot of good land - they with a significantly harsher climate (lower rainfall, more extreme temperatures) than the paved-over areas on the coast.
The maintenance of some areas in the Sydney basin for farming is part of what makes this city so desirable, but Sydney is also all about making a quick buck and damning the consequences.