Anyone here remember the Jimmy Carter days? Super high interest rates, super high inflation. It lasted more than a short while, it was great as a kid with a passbook savings account paying 12%, for anyone needing to borrow money, not so much. This economy we have now is going to get worse, and it will last for at least 3 to 4 more years.
If and when 100LL is banned, it will definitely put a crimp in the light GA market, meaning that demand for planes and thus prices will drop. While many airplanes CAN run MOGAS, it is not legal to. My 180 is a prime example, there is no STC to run MOGAS. Around here there are only 2 stations that sell non-ethanol gas, and the price is very high. My engine builder for my kit plane told me NOT to run the non-ethanol I can get locally, because it is probably old stale gas.
Like everything else, prices on airplanes will likely never go back to what they were before, but they will drop. The coming economic collapse is going to make 2008 look like Childs play.