My major reservation about re-nationalisation would be 'careful what you wish for'.
Governments of any colour tend to be inept at managing enterprises. It's worse when those governments are socilaist.
The unions would be super emboldened. There'd be even more political favours done, and even more money wasted with poor decision making.
The best course would be to deregulate Australian airlines' domestic travel and hence allow the likes of Singapore Airlines a true go at instilling 'service', 'punctuality' and 'reliability' into what at present is most definitely a network that exhibits none of this.
Proper high speed rail also must be built on the lower east coast: Brisbane to Melbourne via Gold Coast, Coffs, Sydney, Canberra and Albury/Shepparton). This would really put the wind up the airlines' sails!
(I agree: SQ had a previous chance, but times have changed).
Internationally, while there are some problems (Sydney Airport for instance has limited or few slots available for new airlines, even if we rid the airport of alleged hoarding by QAN), surely the optimal course would be to allow new entrants such as Turkish Airlines and existing ones such as Qatar Airways a significant number of new flights, and extend that to any other carrier, limited only by infrastructure constraints. (Yes, existing bilateral and other agreements are complex but again, these can change if there's political will).
(20min delay)