In my experience, most retirees have more rooms/land than they can make productive use of. I feel that there should be some pressure for them to sell that property to families who can use it more productively. That's the stick, but I feel there needs to be a carrot, where builders are constructing homes that these retirees will be drawn to. There are retirement communities in the southern US like "The Villages" https://www.thevillages.com/, but as the population here ages, we need to build these everywhere so retirees can move into the communities that meet their needs without being forced to leave their cities.