In his press conference re the death in WA today, the Premier said "The modelling indicates that potentially, in late April or May, there may be greater spread of the illness here in Australia, and at that point in time obviously we would need to ramp up some of our activities. The peak would then hit us in potentially August, which is obviously not a great month because our coldest months with the highest level of flu."
This claim is a little dubious, though I can understand why it was made.
There simply isn't enough data to be able to make any clear predictions right now. Something important to consider is that even today, well over 90% of all cases are from China. The only places to even have more than 100 cases aside from China are Korea, Japan, Iran and Italy. It's relatively well controlled in Japan, and Iran is no the travel ban list.
The main firewall for us here in AU (and most of the other more isolated places, e.g. the US) are the EU countries. I'd closely follow what happens in the UK, France and Germany over the next two or three weeks. The number of active cases have been falling and falling for quite some time.
Again, take what I say with a grain of salt - I'm not the Department of Health, but hey, I did top my epidemiology class when I was in medical school.
Regarding the actual deadliness of the virus, what we know now is that it's more infectious than the flu, but in healthy adults, the mortality rate is unlikely to be very different. In people under 70 (or maybe it was 60, I don't recall exactly), only 0.2% of cases are fatal. On top of that, in a country with more than 1 billion people (China), there weren't even 100,000 cases, meaning that less than 0.01% of the country was even infected.
My point is that it's not going to be doomsday. We will converge to one of two scenarios:
1) It never really reaches AU in any meaningful way.
2) It becomes an illness like the flu that 0.01% of us will have to deal with. If we parallel the infection rates from China, then 2,500 people will contract the illness in AU.
To keep it all in perspective, you have a far, far, far higher chance of dying in a traffic accident than you do of contracting and subsequently dying from this virus.