I know that this would not happen but how is this for an idea?
Alan could try to raise capital by convincing the big four Australian banks to invest $500 million each, this additional $2 billion of Australian ownership would then allow for further foreign investment of up to about $1.9 billion. If all that was to happen it would more than double the market capitalisation of Qantas. This injection of funds would allow Qantas to compete with any predatory behaviour, or to expand their operations, or to provide upgrade/superior services across their fleet (eg. Inflight entertainment for Qlink, Wifi internet on all flights, more new aircraft, etc) or perhaps do all three.
Obviously the banks and any other investors would want to see a return on their investment so they would not want to see their money simply thrown down the drain on a strategy of undercutting any competition on ticket price alone.
If this funding was to happen it would help show if the alliance of Virgin Australia backers are simply injecting funds into Virgin for predatory purposes because to continue the strategy they would then have to invest a lot more to keep up or alternatively they would walk away. If their strategy is not of predatory nature then they would maintain their current level of investment or slightly increase it and Virgin Australia would compete with offering a superior service to Qantas (I am not saying Virgin isn't trying this already).
As I said before, I know it won't happen.