The Saudis are undercutting a multitude of enemies. Obvious...

The Saudis are undercutting a multitude of enemies. Obvious enemies are shale oil producers in the USA. As well there are the deep water wells. A bonus is to damage both Russia and Iran for which the Saudis have a racist hatred.
Looking beyond the obvious ones is the threat posed by electric cars. These are fueled by coal burning powerhouses, no need for oil.
This electric car angle was mentioned on SKY today by the way.
So looking ahead and if the Saudis are smart then they will pump for all their worth. If so then the AUD should stabilise.
I see the demand for electric cars coming from Nerds who worship any new tech. This could be a max 10% of the population. For Tesla these are wealthy guys who will always want to get the next model a la Apple phone devotees.