It is possible for a national airline to fail ? Look at Swiss Air and Sabena. Will QANTAS fail ? Probably not, but will things continue in their present form ? I doubt it.
If a company can make enough profits to support gross inefficencies and pay staff well in excess of the work they perform then fine. But eventually someone comes along and spoils the party.
The UK print unions were having a lovely time until the 1980s when the Star newspaper started up with new technology and working practices. A printer on a national newspaper earnt twice as much as an airline first officer, for one or two nights work per week, and could not be sacked.
The United Auto Workers at General Motors were on a good wicket too, until the Japanese and Korean car makers came along.
And who wouldn't want to work for an airline ? Be a unionised baggage handler and earn more than a turbo prop pilot. Be senior cabin crew and collect close to a first officers pay even though you are well past your prime and spend your work hours in the galley complaining about how things aren't what they used to be. Best of all, be a senior Captain on $250 000 with a defined benefit pension doing one or two nice trips per month and reserve the rest of the time, flying < 500 hours per year.
Now we have low cost carriers, non union (except South West), low overheads, efficient (same work with fewer people on less pay in less time), lower terms and conditions while working to max.
In future there will be two choices, low cost - low service or full price - full service. If you want to be the latter your product must justify the extra, and you will have to trim the fat to make difference reasonable. An extra 30 - 40% you can get away with IF you are reliable and give value for the premium. Charge an extra 200 - 300% and the issues with low cost airlines become a lot less important compared to the savings.
A smaller QANTAS with new aircraft on a reduced network with the fat and unsustainable working practices removed could be a serious contender. Singapore Airlines and Cathay are obviously able to justify their prices to those who will pay more for service. Unfortunately these people are heavily outnumbered by those whose only concern is price.