What do we lose when our old suburbs disappear?

I live on the edge of Parramatta, Australia's fastest-growing city, on the kind of old-fashioned suburban street that has 1950s fibros constructed in the post-war housing boom, double-story brick homes with Greek columns that aspirational migrants built in the 1970s and half-crumbling, Federation-era mansions once occupied by people whose names still appear in history textbooks.