[Jasoncw]

It's more common for the existing stock to basically exist as-is, with some remodeling.

If a suburb full of ranches is built and that area becomes more expensive it's still going to be almost entirely made out of ranches, but with better landscaping and remodeled interiors.

It would take a lot of time for those occasional rebuilds to wholesale replace a neighborhood.

It goes in the other direction too. Rich neighborhoods that are now ghetto are still mostly the older fancy buildings, with newer cheaper ones mixed in.