One new Melbourne style outbreak and we’re back to square one
I doubt it will go back this far. Better contact tracing and early managing of COVID clusters or hotspots should avoid the need for mass border closures again. Even Chairman Dan probably recognises this.
Also, bear in mind the QLD and WA border closures were more related to state elections than COVID. Politicians can't help themselves and won't waste a good crisis if it advances the chances of re-election. But these elections will be done and dusted by March 2021. There will be much more pressure on the WA Premier if he finds that everyone else is open.
My hope would be that by December, border restrictions along the east states would allow at least a 50% domestic service.
International services - that's a much more long term process.