For some reason you made me think of this -
Which is really weird since I saw it once, years and years ago.
I believe many of these companies will,, as you put it,
maintain the efficiencies they've discovered. I dont want to be a nay sayer but I do not believe a rise in economies will result ia a raise in employment. At least not immediatly anyway, it will take time.
I also think that investiment needs to go into new employment opportunities, the U.S still has a lot to do to effect real change in its climate change policy, in my opinion. What about setting up new companies that build wind turbines and solar panels etc. These industries have viabale financial futures if the government can push these incentives through. I will use Las Vegas as an example, it's in a desert isn't it? Lots of sun
Put as many solar panels as you can on the roof of as many buildings as you can, and presto, new jobs created, carbon emmissions reduced. Now apply this on a national scale and think about the possible implications.
Thats just an idea I have at least