Unless you're going to be flying Paid C or F in QF/NZ, it's going to be very difficult getting status with them.
Also, Award flights and upgrade redemption levels are "high" (QF/NZ) comparable to UA. (Obviously not possible to make direct comparison given the variables, just generally speaking)
I think its very premature to think UA is pulling out of Australia. Airlines share and jointly operate lounges all over the place, not necessarily a sign of 'giving up'.
Personally I would prefer loosing a dedicated lounge rather than another experienced UA staff member with the ability to assist with the more complex queries and requests at the airport...