You don't need to confiscate anything. We have an abundance of housing stock (nationwide, many more existing homes than families to fill them). If you make it impossible to be a private landlord then these properties will decrease in value until most citizens can afford to buy a house. Public housing will only be necessary for a small percentage of outliers. New housing will be built to be sold at a modest profit and replace decaying stock, just as it is now. The only difference is owners will not be able to sit on the pot collecting rents from derelict buildings while they wait to optimize their redevelopment in a peak market.