The article is paywalled so if not against copyright or AFF rules, could someone please paste it in full?
ozflyer, fair enough sentiments but perhaps a few things to consider.
Lately IIRC Oz flights typically carry close to 50 per cent of passengers who originate from here, and 50 per cent who originate from overseas (I'm talking journeys, not ethnicity or citizenship.) It varies by route though.
Most international air fares are booked at least a few weeks in advance, sometimes far longer, even though travel agents claim that many are booking closer to date of travel than was so a decade ago.
Not everyone will cancel: far from it. Some people will regard any 'threat' as overstated or irrelevant to their destination. Another group may be so looking forward to their holiday that they'll still go. Some will have important business deals to close, and others family events like funerals, weddings and baptisms that they woudln't counternance missing.
And then there's those who won't be able to resist any drop in air fares and accommodation costs.
Some providers may not refund costs incurred by travellers (you'd hope that was wrong, but I daresay not all will come to the party.) So being unable to easily recoup costs may be a disincentive to cancelling. Unwise as it may seem, not all travellers have insurance (and perhaps some policies may exclude cancellation costs, or alternatively have a significant excess per claim.)
Still, it's a developing situation so above is far from definitive. (Let's see how wrong I was if assessed on above post-Easter 2020.)