Have a look at the graph of the cost of delivering utilities. This isn't about environmental sustainability as much as long-term economic sustainability.

When towns sprawl, utilities with costs that scale with distance cost more per person.

That StrongTowns blog graph is intentionally misleading. It's not a cost of delivering utilities, it's a cost of utilities based on tax revenue a given parcel generates. It's an attempt to make cities "for profit".

Obviously, anywhere significant amounts of people live is going to come up "red", because we don't tax people the same rate we tax corporate offices, and because people use more resources there (most people live / cook / shower / sleep / etc at home, not in their cubicle).

That doesn't make it less worth that cost though (those downtown regions are only able to be "green" because there's lots of red around them). And it doesn't really have to do with sprawl. (The cost does rise with distance, but in mostly trivial ways. And those costs spiral backward again too -- 5,000 feet of new powerline in suburbia is far cheaper than 500 feet of new powerline in Manhattan, for instance).

> This isn't about environmental sustainability as much as long-term economic sustainability.

If that's the argument, then cities are almost entirely ruled out already. Cities aren't even economically sustainable for their current residents today, sprawl is the only thing preventing cities current economic issues from becoming even worse.

Sprawl is the only reason the majority of regular folks have any housing to sleep in at all.

When factored in with total cost of living are these cities cheaper or more expensive? I can think of plenty of dense efficient cities that are more expensive than cities with sprawl.