I am no expert Kcockayne but I have followed the goings on at the airport & by extension the oil industry since the early 80s. You're right too - sometimes things take a turn for the unexpected! However this downturn is the most serious by far & when the N.Sea is in its mature phase & when costs were allowed to spiral.
There may come an upturn of sorts, but for every upturn when the price rises there comes - eventually - a drop in price & the next downturn. The oil industry has always been cyclical, & it is more important now than ever that the region diversifies somehow.
Anyway back to the airport & Flybe have commenced the Newquay route. Good luck to them & who knows - maybe one day we'll see Exeter return.