when you are young, as you age a number of things happen:
Your relative fuel costs will also rise as rivals renew fleet.
I'd be interested to see where we are in 15 years. Gulf states can offer keen terms for their airlines as they don't have to levy corporation or income taxes, but it isn't all rosy as education and health costs still have to be paid for. In the longer run, oil revenues will fall off (Dubai already is a trading city, not an oil producer) - and alternative fuels will be found. This may mean these economies move closer to western taxation models, but for now they still have a huge head start.
I see point to point flying for longer haul routes becoming the realm of the wealthier passenger, with the cheapest fares only being available with a change - in a way which is even more stark than what we have now. Ironically of course, the short haul flights will still be dominated by point to point.