I know of some related things going on here: * Typically in Germany, social housing is built with a time-limit built in: after X years, the house falls out of

I know of some related things going on here: * Typically in Germany, social housing is built with a time-limit built in: after X years, the house falls out of the social housing program and can be rented and sold freely. At the moment, a lot more houses leave the system then are added. * Many cities sold their real estate after the financial crisis to give the money to the failing banks. I.e. Berlin is super-broke, in parts because of a big banking scandal of the previous government. * In Munich they have a pretty decent system: anyone who develops land had to keep to a certain split of social housing, middle income housing and free market housing. They use the land they own and their powers over zoning to enforce that.