I don't see how deaths could possibly get that high, NSW looks to have peaked at around 1600 new cases i think? Peak daily deaths I don't even know, but quite low. Even IF Vic got to 4400 new infections per day, why would daily deaths be multiple orders of magnitude higher than what NSW has seen, add on top that by December we'll have much higher vaccine coverage than what NSW has currently.
IDK, maybe some of their 'scenarios' involve only providing patients with Trump recommended treatments and Australia's entire vaccine supply chain just vanishing??
We've now had a good 18 months of charting outbreaks all round the world with various levels of mitigation tactics employed. Nowhere has it just continued to skyrocket, I mean look at India with a pop of 1.4 billion, they peaked at 400 000 cases per day against Delta and now have a pretty steady 35000 cases per day. Scaling for Australia's pop that's 7300 peak and then dropping back to 640 per day. I'd like to think our health care system, vax coverage, and infection mitigating strategies, we're in a much better position to achieve a far more favorable outcome than what India have managed. (Even IF you take into account for massive under reporting that likely was/is going on over there.)
EDIT: Stoff posted while I was typing, numbers still seem a bit pessimistic to me.