Historically Western Australia has always had a strong secessionist movement, dating back to even before Federation, when the colonial government lobbied Parliament for permission to become a separate colony from the rest of Australia. In 1933 a secession referendum received a majority of the vote, but as Australia was still technically a British colony, London refused to grant permission.
In recent years the mining boom of the 2000s has reignited the secessionist movement, and it has a large amount of support in WA. Basically, how can the secession of WA into a separate country happen, and what would the repercussions of that be for Australia and the wider world? Any time after Federation is acceptable, but bonus points are awarded if it can happen in the 2000s or later.