At the current rate of vaccination the USA will be fully vaccinated in a few months. Cases there will decrease significantly and perhaps even to the point of eradication?
Two things will then occur. They’ll be able to travel a bit more freely, and more vaccinations will become available for the rest of the world including Australia. Whilst the Australian vaccination rollout has been slowed with the AZ issues, I can foresee a very significant number of Pfizer vaccine doses coming online from about August with the prospect of the entire nation vaccinated by Feb/ March next year.
With that having occurred theres no reason why quarantine free travel can’t open up from Feb/ March next year as long as the state Premiers start to understand that Covid cases with vaccine is a very different beast to Covid cases without vaccine. My guess is that a vaccinated public will start to turn against state Premiers who continue the lockdown charade. In the interim I can see bubbles with Singapore and Japan before years end. Potentially the USA and the UK also though there may still be some iso requirements for the latter two on arrival until all of Australia is also vaccinated.
A lot of has changed in the last 12 months. A lot can change again in the next 12- both good and bad!