I'm sure they'll eventually put solar panels or something into the roofs of airplanes.  Otherwise, I see airplanes being the last thing on the list so far as getting the green treatment.  It would take a lot of engineering and a huge amount of expense, which the airline industry isn't going to pay for anytime soon.  Also, there are much bigger fish to fry, so far as pollution and green energy are concerned. 

I've had the same thought before - will air travel (at some time in the future) become socialistic with the government in control of one single airline?

Boy, that would be scary.  I don't ever see it happening.   The airline industry is based on supply and demand just like any other industry.  There will always be a need for air travel.   With gas prices high, and demand for travel slowing,   bankruptcies and consolidation will continue.  Routes will be cut/reduced.  Less choices means more pricing power for the airlines that are left.

When the military has completely analyzed all 'alien spacecraft' and found it to be a useful flight tool they can build themselves and the government allows it to be released so they can accordingly tax and regulate it and...oh wait thought this was the x-files fan club message board...lol

Kidding of course. The truth is that 'greener' fuel is the only way in the near term that the airline industry will be going green or anything close to it. Maybe if they could collect the emissions in a container on the plane than whenever the plane passes one of those holes in the ozone they could shoot it out straight into space. (again kidding..or am I?...insert X-Files theme music)