I could not disagree more....
Since the advent of the 747 aircraft airfares have been getting cheaper and cheaper....
Ummm, since the advent of the B-747 (first commercial flight 1970), to the late 90's, oil was pretty much under $25 bbl, with the exception of the oil crises of the 70's.
Oil has only been above $50 bbl since 2005, dipping earlier this year during the GFC to the low $30's.
So high oil prices (for arguments sake, above $50 bbl) has only been in the last 4 years. Not enough to change the long-term decline in ticket prices, which were more the result of de-regulation, A scales being replaced by B scales etc. Some airlines did introduce fuel surcharges though... to not affect the low fare price.
Maybe I should have been clearer, and said the Airline Industry is
now (from 2005) in decline...
I can't really see anything in your post which shows that you disagree with my contention that Airlines are in decline.