Bi-pedal Life

In my search for the awesomest place to live, I came across a website called Walkscore that rates neighborhoods and individual addresses by their walkability.  They take into account an address's distance to all sorts of things: stores, schools, parks etc. and gives points when they are closer than 1 mile.  It's lovely to look at the rankings of the top 40 most populated cities... look at the map of San Fran, then look at Jacksonville FL.  How will it survive?