The all-steel Lustron was supposed to be an elixir for many of the housing problems we still face today. The house looks like it’s from an era that never happened. Tucked on a side street of a tony Dallas neighborhood filled with McMansions — and around the corner from actual mansions that sell for more than $2m — it stands out at only 982 square feet. The land beneath it is valued at more than double the actual house. Built in 1949, it’s not the only mid-century home in the neighborhood. But th...