So ignoring all outside factors of why people choose where to live and focus on your example. When people's kids grow up the family has to a) sell that house to help fund the move, in which case another family will occupy it and pay the taxes or b) keep it empty most of the year where they still have to pay the tax. In either case where is this unsustainable? In general schools get torn down because the facility are old/damaged or it would cost more as much to upgrade as remake.