What I find is odd is that the new NZ schedule for AKL-HKG-AKL is similar to that of the AKL-HKG-LHR schedule, which means very late departure from AKL - early arrival in HKG, then an aircraft sitting in HKG all day until an early evening departure and late AM arrival in AKL.
This requires 2 777s rather than 1, which was the old operating pattern of an early PM departure, late PM arrival in HKG - 2 hour turnaround with an overnight back to AKL (which parallels the daily CX flight).
Whilst I can imagine CX would want NZ to maintain its current schedule, which may suit some connections onwards from HKG in the early AM, it does tie up an additional aircraft. The only way that would work is if the yields from such connections are very good, the loads are better not competing directly with CX and NZ is now able to price more highly given the agreement with CX.
What else it does is limit NZ's ongoing connections to Europe (if not China) to the CX daylight flight to LHR. Given how HKG has been useful before for connections on LH to FRA/MUC and LX to ZRH, it's a little surprising that NZ has given up on this, and sees the LAX connection as superior - which it most certainly is not.