SYD (33°56'46"S 151°10'38"E) ORD (41°58'43"N 87°54'17"W) 9232 mi
AKL (37°00'29"S 174°47'30"E) ORD (41°58'43"N 87°54'17"W) 8184 mi
According to Great Circle Mapper SYDORD is longer than the promised range of the 787 or 747-800 - AirNZ can do a non stop from AKL, QF would have to stop somewhere (ie AKL).
QF did announce a plan to serve ORD with its own 747-400s, the MEL-LAX flight was going to continue to ORD. The plans went on the back burner after 9/11.