According to the Herald:

Air New Zealand was currently recruiting Shanghai-based cabin crew so it could ensure there were adequate numbers of Mandarin speakers on all flights, Sims said.

It was crucial to cater to the needs of the Chinese customers and that would also be reflected in the inflight menus and the entertainment.

which seems to imply partial staffing of the PVG route by PVG-based crew rather than 100%.

OT, I was looking at the timings for the new NZ service and am not sure they have been well planned in terms of considering the market they are aiming for (ignoring aircraft rotation slots for the time being). With an arrival time in Auckland of 1:45 am, people are going to have to shell out for an extra night's hotel room (this will probably impact most on tour groups). Whereas those wanting to come here could (say) leave Shanghai as the same time as the Air NZ flight (8:55 am), transit through Hong Kong and pick up CX117, which arrives a few hours later in the early morning - the advantage being they can launch straight into their holiday. Believe it or not, this tactic is used by HK tour groups with great success (HKers hate being 'cheated' out of a day's holiday, and I'm not sure Shanghaiers won't feel the same way).