[dalbasal]

Apart from some exceptional circumstances, towns and cities stay where they are.

Exceptions are frontier towns, mining booms, war torn cities.

In 99% of cases, cities stay where they are, bankrupt local authorities or not. Populations decline a little. Quality of life declines a lot, but the problem doesn’t just go away.

And anyway, what does unsustainable mean? What can’t be sustained exactly? It sounds like what can’t be sustained is the financing model for poor localities. Why not walk away from that?