Nonsense on the interest rates theory since we had instances in the 1980's of rapid price run-ups with mortgages at 15%!    The interest rates depend mostly on the inflation rate and that determines what people can afford.  If  you get say a 5% wage increase each year, then you will be making more than twice as much in 15 years and it influences what you can afford if you can carry the first few years.
 I also challenge this theory that there is something terrible about sprawl.  Eventually most people either get used to a long drive or shift to work that is closer to where they live.