To start with, have NZ actually said that they will fly non stop from Australia to USA . You stated "Air New Zealand has purchased the 787-9 to fly from Australia and New Zealand to North America," ; if the flights to North America are via NZ, that would be a disincentive already
Also, wil Jetstar be competing on the same routes? At the moment the information seems to be that JQ will be offering MEL/SYD-HNL-USA ; unless NZ is planning to offer the same route, then I see no direct competition from them anyway; atm, other than QF, I don't know a carrier other than Hawaiian flying SYD-HNL
Dave