Well, you have German cities with 20% share of transport on bicycles, another 50% by bus, tram (light rail), subway and the rest is individual transport via cars.. Some progressive cities in Holland or Skandinavia are doing even better than that.. Some scattered parts of the US Northwest is slowly heading in similar direction.
So powerdown is possible and could been done globally in gradual manner over a couple of years.. The only break is psychology not technology or money..

