WI, the US and Australian Governments force MacArthur into having all Allied ground forces - US, Australian and New Zealand - commanded by General Blamey?
Was Thomas Blamey part of the group that advocated abandoning northern Australia and establishing
the defensive Brisbane Line? That would have been a major change in strategy from MacArthur's command if Blamey had in fact favoured the Brisbane Line strategy.
Also going forward I would guess there would be little support from the Australian government to supply forces for the liberation of the Philippines and operations in Indonesia. After the Papua New Guinea campaign I would guess that the South West Pacific Area would become an American led command anyway simply because of the size of the American forces build-up.
I am fairly sure that the "Brisbane Line" idea was before Blamey got back - though I am open to correction. It is also worth remembering that Eddie Ward, a Labor MP and Mac both talked a lot of guff about the Line for their own political benefit.