Was having a chat with a QF insider about the upcoming JFK route - apparently the dispatchers and related planners are scared coughless about how things are going to run if/when crew run out of hours. This might occur due to the length of QF4's JFK-AKL segment, in case of delays out of JFK and/or unforecast headwinds. East/northbound if QF3 departs AKL late, they can possibly divert to LAX or DFW, and spare B787 crews should be available there to continue to JFK (possibly at the expense of delaying another service), however this has a low chance of being needed due to winds aloft being favourable eastbound. But west/southbound on QF4 they are very worried - the diversion point is NAN but there is no B787 crew base there. In addition, the timing of QF4 (AKL arrival at 05:00) means that even though they would have considerable heads up that a replacement crew might be needed, there is no scheduled service on any carrier that could take the crew to NAN in time. For the launch, the plan is to have a chartered 737 on standby in SYD that can fly a spare crew to NAN overnight if needed, to avoid a PR disaster if the first flight(s) get stuck in NAN. At the moment it's unclear if they will need to continue this for the foreseeable future.
Note: I asked about DFW-MEL since it's actually longer than JFK-AKL, but my contact thinks this not a problem as the plan would be to divert to that flight to AKL, and with enough notice they can typically get a B787 crew from SYD to AKL in time, on the existing evening AKL service.