VA has until October of this year to use the HND slot, iirc. The slot can not be 'wet leased' out to another operator as the slot if for 'Australian Carriers' and it'll has to be on their own aircraft.
Out of the previously discussed "fantasy hypothetical" decisions, either via 'GUM' 737 or a 'damp lease' of widebody aircraft (VA providing the FAs and the pilots from elsewhere), the aircraft would have be painted in VA livery as well (perhaps with a small operated by (AOC number/operator) below the door, for the HND slot is minimal.
If VA were to damp-lease widebody aircraft (where chances are almost close to zero), it would likely be paired with BNE-LAX, as UA will not be flying BNE-LAX for the foreseeable future unless if UA gets a 'favourable' Queensland Government subsidy (or effectively Queensland taxpayers paying for the 'charter' of up to '2 UA jets') to fly BNE-USA for the (quote Premier) "sake of tourism and competition in Queensland, which is 'good for Queensland'" - (/quote Premier).