Well, just as a measure of what the current fuel price does... I'm still operating about 370 DC8s on long haul and right now I'm just about breaking even across the whole airline whereas before I was one of the most profitable (typically around 30% gross profit). Once profitable routes are now marginal or loss makers. Particularly, the smaller -62s are just about useless and I have over 200 of those. No complaints - I deliberately planned it like this so I could see how I'd fare. The ULH routes with stopovers (South Aisa, Australia from the US) are all making losses, even on -63s.
One of the main problems is that my load factors have dropped off as the planes suddenly became "too small for this route" when the wide-bodies were introduced. Interestingly, this even seems to affect the routes where there's no competition with, for example, load factors on my SFO-SIN (with stopover) dropping from near 100% (with prices at 30% above default) to between 30% and 50% even though I am under serving demand, have no competition and have lower than average prices. I thought it wasn't supposed to work like that.
Anyway, I'm digressing. Let the fuel keep rising - I wish there were a few years left of the game so I could wipe out some of my competitors who must surely be in a worse state than me.