AOPAs single largest concern is flight training starts and certificate completions. It really is a base level concern. GA flying hours down, the costs of everything from regular MX to engine overhauls goes up due to volume inefficiencies. Look at the price of a gallon of AVgas. How much is a C172 rental at your local FBO? This is about the money, or lack of it. Price the 0-to commercial package at AllATP, then add 1250 more hours to complete the picture. In today's economy who has that kind of cash, because banks nor the federal government aren't loaning nor guaranteeing aviation training loans.
This industry has spent the last 60 years exploiting pilots and it finally is reaping what it has sown.
If you want to look at most regional newhire classes that will tell the story, recycled pilots from other regionals is just shuffling of the deck not adding to the count overall. Want the truth, follow the money trail. The regional industry will eat itself from the sphincter in and when that is complete, the majors will have their bite at the poo sandwich. The truth of the matter is, pilots are highly trained machine operators, with a lead time involved for the training. Airplanes are expensive and even more expensive when they aren't flying. I was around for the Kit Darby years and have been in the airline industry since, these are different times, vastly different. The cost of GA and training is the primary difference.