True that the 777, 787 and 737 have more efficiency, but the market situation of the aviation fuel is pushing more airlines to bring back the older planes because they are cheaper than signing new leases. For example, Southwest is buying older 737s because its cheaper to run them because of fuel prices:

http://www.bloomberg.com/news/articles/2016-0...-down-jets

I am curious as well what is being done with the 747. The value of the plane was valued down to 0 on the last financial statement.