There seems to be numerous factors working against GA: skyrocketing operating costs; decreasing numbers of licensed pilots; closing airports; and the ever present threat of banning LL gas. At what point does the used plane market collapse?
"There are over 19,000 airports, heliports, seaplane bases, and other landing facilities in the United States and its territories. Of these, 3,330 are included in the FAA’s National Plan of Integrated Airport Systems (NPIAS), are open to the public, and are eligible for Federal funding via the Airport Improvement Program (AIP)." (http://www.faa.gov/airports/planning_capacity/ga_study/media/2012assetreport.pdf)
That means over 82% of airports are privately owned and used - and so operations in and out of them cannot help but subsidize (in some small way) the 18% that are public use airports.
