First of all, the whole everyone is going back to gas powered trucks just isnt true. That was all hype started back in the 6.0 liter days by pissed off customers and internet jockeys. All the big three still have tremendous sales in the diesel truck market. In fact, dodge just released a half ton diesel option, and Nissan has plans to do he same shortly. Diesel still sells, quite well actually. According to this article,
http://www.trucktrend.com/features/news/2012/163_news120418_diesel_auto_sales_increase/ diesels account for over 50% of new 3/4 and 1 ton trucks sold, with consecutive monthly gains year to year. Its also interesting to note that diesel powered automobile sales in general were above the board with continual annual growth, and starting to exceed hybrid sales. Diesel is here to stay.
As far as the state of the economy goes, it has much more to do with poor consumer decisions, and lack of regulation of the stock market than it has to do with the price of automobiles.
And I have looked around, and I find the real problem is with the people themselves. They are unwilling to change with the times and keep trying to re-live some iconic image of the past that never really existed to begin with. I know of several companies, off hand, that are doing INCREDIABLY WELL right now, and its because they got with the program. The whole economy isnt doing badly, just the sector that isnt willing to do anything about it.