I guess I am too cynical to think that people will do this out of altruism.  It is far too ingrained in our nature for us to do whatever the hell we want.  The only thing that will force a more responsible attitude is higher prices.  For gas, for meat, , for oversized housing, etc.  With higher prices, people will figure out how to adapt on their own.

The transition will take time, of course, and aspects of this are outside of the control of the individual.  Things like availability of mass transit, for example.

I hope we have that time!