^^ Well majority of the international cricket stadiums are situated in south Australia, so don't know if Western Australia can afford/able to host complete tournament alone, how many international cricket stadium they have except WACA and perth?
The advantage with Australia is that they have a good number of stadiums, where first-class matches have been staged. These stadiums can be used to host the international matches, as a last resort. Also, there are many dual purpose stadiums in Australia. During the cricket season, they are used for Sheffield Shield and BBL matches, and during the football season, they are used for the Australian rules football. A few such stadiums that come to my mind are - Subiaco Oval, Claremont Oval and the Bassendean Oval.
That said, the main venues are going to be the two international stadiums - WACA Ground and the Optus Stadium.