The trouble with that is the mask's suppress contribution of the virus, but have minimal resistance to acquiring the virus. When NSW opens up I would suspect most vaccinated will discard the masks.
Whatever the free range % of virus susceptibility will translate into 30% of the unvaccinated population. I'm not sure if there is a test bed where no restrictions occurred to get an idea of unmitigated contagiousness, but England is reporting a steady state ~20,000 since July. for a population of 56M. That would translate into ~3000 per month NSW. .
