Speaking about ExxonMobil only and with a little inside knowledge having worked for them for nearly 30 years.
They always said that the downstream operation in Oz was a licence to lose money which is why Esso sold out years ago. When Exxon and Mobil merged they where then lumbered with a downstream side again but that has now all been sold off. (The few 'Mobil' servos around are private and not company owned.)
Will they pull out of Australia? The company is very cautious with money and would do anything ethical that would lead to a long term profit, so the refineries could be sold or closed if necessary. Having said that they also have a lot of other infrastructure in this country and have just spent approx $5US billion on upgrades and expansion in Bass Strait and also have huge of assets up on the North West Shelf and in PNG.
See:
ExxonMobil Australia
Slightly OT but just trying to put a little perspective in the discussion.