One solution is to upzone. Successful cities have trouble building housing affordable to lower earners when the land becomes too expensive for developers to target low to mid-range apartments. The increased capacity relieves the city of the burden of subsidizing housing on expensive land, and justifies greater infrastructure expenditures. Of course, you'll have some old timer NIMBY holdouts who will resist, but when the situation gets bad enough and losing their house to a ghost town is an imminent and the only alternative, many will probably change their tune.