A major cause of the rise of the oxygen thieves is the media, and consequently politicians, obsession with legislating away all risk. In the case of GA that is further reinforced by the media obsession with any aircraft accident, where ever it happens. Any light aircraft accident in Australia will be reported with a summary of the accidents in the area over the previous 10 years. These reports are also reinforced with ignorance and an absolute disregard for facts.
Simialr reactions arise from motor vehicle accidents involving the "immortals" males between 17 and 25! The media seem to believe that more laws will stop those who disregard rules as a matter of course.
One thing we in GA could do is ensure that our representative bodies do what their US counterparts do - provide an effective factual response to every such report and to also be more pro-active in promoting the benefits of GA. We usually only seem to tell those stories to ourselves while complaining that we are having a hard time.
I am not sure that all of GA is dying. Look at the data in the CTAF thread and the CASA and BITRE reports. Aircraft numbers are up, flying hours are slowly improving. 3500 RA-Aus aircraft and 1800 amateur built VH registered aircraft are not signs of death. Twenty years ago there were only about 350 amaueur builts on the VH register.