I believe the only primates Australia Zoo currently has are ring-tailed lemurs. Black and white ruffed lemur and cotton-top tamarins are no longer there to my knowledge. This has allowed Wildlife HQ to establish a point of difference, by building up an impressive primate collection. I’m mentioning this as point of interest, as I’m not aware of an agreement existing between the facilities to maintain this arrangement.
Ambitious projects would be an aerial pathway system for orangutans; or even a Congo precinct. It’s not hard to imagine something like this would have eventuated under Steve, who in the mid-2000’s had plans for a North American precinct, an Asian precinct etc. Savannah species would have likely been rounded off with lions and some antelope/ostrich joining the savannah; perhaps followed by pygmy hippopotamus, mandrill, colobus, bongo and gorilla. It’s sounds too ambitious too happen, but that was Steve’s way of thinking and one can only wonder as to what might have been.