An answer could be land trusts. A land trust that is sufficiently capitalized would be a capital partner to help buyers buy at current market rates. When these new buyers sell, the land trust stipulates the price they can sell at. We have these to a limited extent in New England, and they may exist elsewhere. The problem is, at this point, only a currency producing entity like the Fed would seem to have the wherewithal to capitalize such an endeavor at a scale needed to substantially change things.