It's interesting analysis from Macquarie but if interest rates rise, demand for domestic air travel may decline (or fail to increase at the same rate, or above, population growth.) Yields might also decline.
QFi's operations are profitable but some routes are not (I'm looking at you, LHR) and competition is very fierce for our traveller dollars, pounds, Euros or pesos.
If one looked at the last decade as a whole, QF's financial performance, overall, has been poor. It's better at present but surely it is still subject to the whim of unpredictable events such as terrorism, very adverse weather or an increase in fuel prices as three quick ones that come to mind.
I can see VA imploding, but cannot predict when. If it become a monopoly, Qantas might then face increased scrutiny from government as to its fares, or even allowing foreign airlines to carry passengers domestically.