I think the WA government should designate another major city, and start investing now to build it out, otherwise our housing issue will be worse than any other city in the nation. Perth's shape (oval), and the lack of largish regional centres in this State will supercharge housing constraints if people pile in without major forethought by West Australians now.
In regards that, I think we should try for a major northern city. I listened to Ken Henry and he was pretty convincing on Port Hedland (i think) being developed as a major port to compete against Singapore, with it's major selling point being the avoidance of the constricting Strait of Malaka. Good for a less stable and unpredictable world.
Otherwise it would have to be committing to Albany or Bunbury becoming far more major than they are now.
An option would be investment in a Bunbury based rare earths hub, including mining company divisions headquartered there, mine sites, education, and all community services and housing all taken into account.
It would be a serious and highly contentious expansion of mining in the south west though. Serious preparation and protections for the forests would have to be carried out. After all these Alcoa debacles down in Pinjarra, i'm not confident thats possible.