The very most urban core is already dense enough with skyscrapers etc. What zoning liberalization means is primarily two things:

1. Upzone single-family housing with aggressive setbacks from the road and neighbors with wall-to-wall three-story multiplexes.

2. Replace expensive community review processes that allow neighbors to extort concessions out of developers with by-right zoning rules.

> I still think bulldozing 3% of a city’s built environment in 5 years time seems extremely unlikely, but YMMV.

Having the average age of replacement of a building be at 150 years old would result in approximately 3% of the city being replaced every 5 years. That seems a bit long to me, but within reasonable expectations. I would expect to see more than 3% of the city replaced every 5 years.

This is a sloppy essay - it reads like the first draft of an idea. The facts he cites are all true, but a lot of his conclusions are ... sloppy. But it feels like a stream of consciousness, a devil's advocate argument with himself, and it has a pretty good conclusion. I think most of the confusion comes from people who say "zoning" to mean "structural restrictions on growth in the housing supply", while he enumerates those structural restrictions.

Worth a read.

The existence of zoning regulations before 1930 is sort of irrelevant because they didn’t specify 20 ft setbacks and 1/3 acre lot minimums. Those came with suburban planning.