Housing investment would be 'housing starts' as in new houses being built. I doubt that prices will be going down if there are more people and the same number of houses. Part of the market for existing houses is sensitive to mortgages. All this means is housing will actually cost more in the future on a total cost of ownership basis. If you're a renter with a ton of cash, this is good, but for literally all other stakeholders in the market is it ultimately not good.