Always look at the big picture ...
Nice scenario PT, and while I don't think it is pessimistic, it is obviously highly unrealistic.
Airlines earnings historically seem to move roughly in 7 year cycles - though often overlaid by other effects (like economical crisis, volcano eruptions, losing planes for various reasons, epidemics, political crisis, fuel price hikes, acts of terrorism).
As well ... during the peak times every Tom, Dick and Harry tend to found a new airline to join into the money making business. OK - maybe not every, but too many. Virgin and Richard Branson spring to mind as well as Origin Pacific (founded by Robert Inglis, so admittedly no Tom or Harry), but there are many more. Add to that financially strong competitors happy to add the odd flight to New Zealand as well as airlines trying new routes (South America this time?), and what happens every time is that in good earning phases everybody tries to get a big slice of the cake.
Result: margins are rapidly squeezed given that there are only so many bums around but only full planes make money.
Which means ... in my view is the 500m profit before tax estimated for this year already optimistic (but possible, if everything goes according to plan), but the competition will heat up for the 2017 holiday season. I doubt, whether this means just a further 10% drop in earnings (as analysts seem to assume). Margins squeeze in the airline industry looked less friendly in the past.
How do your data look if you assume for 2017 the 500m (I am an optimist ...), for 2018 half of that - and for 2019 again only half of 2018)?
After that (assuming a 7 year cycle) things might move up again.
BTW - just made another interesting observation ... even the professional optimists (analyst consensus at 4 traders) predict for 2018 and 2019 that the AIR dividend will be below 20 cents. They seem to think that 2018 will be the low point, though. Not saying that I trust their consensus, but it is unusual that they are pessimistic related to popular stocks ...