I think this fact is lost on a lot of people. We seem to be of the opinion that the country is somehow special, when in reality we are not.
The virus that emerged in Wuhan jumped deserts, oceans and continents. To think that with over 13,000 active cases growing at now over 1,000 per day will not lead to extensive transmission chains beyond NSW is absolutely ludicrous. It is an almost certainty that the strain in Sydney has now also been "returned" to other countries. If State governments in QLD, SA, NT, WA, assume that they can avoid this outcome then they are frankly mad.
This has (or at least should have) pretty significant implications for international travel, even if just with "bubble" countries.