There is no shortage of fuel, but there is and will be a shortage of cheap and easy to get at fuel.
Thanks to the greens, fuel will for evermore be a source of tax revenue to Governments as flying is seen as sinful. Taxes only ever go up.
The result will not necessarily be less aviation, but the days of mass travel are numbered. One of the reasons the LCC's treat us like sh*t and seem to act in irrational ways is because they know their days are numbered in the long term and are trying to make as much money whilst they still can.
In 20 years, flying will be a mixture of government/military, some freight and very rich people in business jets. For most, a holiday abroad will be something you save up a lifetime for. Bit like a luxury cruise now.
If you want to deny this, then fine, but compare the number of IT carriers with ten years ago and look at what many of the remainder are doing. Ask yourself how the likes of MON or ESY will get on if oil is $300 per barrel and environmental and luxury taxes are piled on top. Read the demands for Jet A1 to be taxed at the same rate as petrol and ask yourself what future exists in this business long term.