Well it’s worth reading the link to see how they avoided that problem in Austria... they had two strategies that seem to have succeeded there: the buildings are on a desirable area of town, and rent does not go up if your income goes up. The second point means that the area ends up being mixed income. You have to have low income to qualify for entry but then once you get on your feet and income rises you get to stay there. So they made affordable public housing that doesn’t become a slum.
