The death of GA
General aviation's decline is not hard to understand if you look at the underlying trends in society today.
1. The advent of the interstate highway system.
The interstate highways system allows anyone with a (cheep) land vehicle to move effortless at 65+ mph to virtually every medium size city in the country. For a trip in an average SE personal aircraft (doing maybe 140 mph) you need to travel well over 250 miles just to break even with ground transportation covering comparable ground. Costing out both (just operating cost, mind you) air approx twice that of land.
2. Small airports disappearing
This is happening mostly in dense areas right now (NE US) but will spread over time as our country continues to fill out. Why?? you ask?? The same reason drive in theaters died 20 years ago. Land values vis the income generated but the business using them. Sure many airport are municipal owned but many more are private, especially the smallest one. The less airports there are, the less convenient for the traveler (not as close to desired destination or farther from departure point) hence a viscus spiral, less traffic, less income (for the airport and its tenets) less income requires higher fees from the remaining users, driving out even more discretionary users (read: causal fun fliers).
3. Lack of innovation in the industry
Some will disagree, but what has the GA industry (specifically engine manufacturers) down to improve the product?? Well avionics aside, not much. Yes plastic planes are finally pushing the 60+ year old technology aside, but were is the increased efficiency?? Boeing and Airbus are forced by the marketplace to offer better fuel efficiency on every new model they produce. The amount of fuel burned per passenger is a sizable fraction of what first generation airliners used especially comparing jets to jets. What improvements have Lycoming and Continental offered from say the 1950's to today's engine?? I wait for the response. If if less that double the HP (or decrease in specific fuel burn per HP) than you have laid down on the job. Today's (new) aircraft compete in the marketplace with aircraft 10, 20 30 years older providing comparative economy at triple or more the cost, makes buy new hard(er) to justify.
There are more reasons why GA is in decline but the above highlights the "major players" in its inevitable decline. Sure some parts of the country will see it happen later, possibly much later but the dream of William Piper and Clyde (?) Cessna that everyone (could) own and fly is far from reality and is destined to be no more than a novelty for true die hards and the rich.