These are my thoughts for any cancellations. The best thing to do is get online and plan your own reroute.
The airline will want to keep you on their aircraft network. e.g. if you’re headed to New York it really doesn’t matter if you fly Auckland to LA, San Francisco, Vancouver, Chicago or Houston.
Much like the Sydney routes you can fly into Melbourne, Gold Coast, Brisbane then connect onwards probably with Qantas to Sydney.
Asia you can probably route through Hong Kong or Singapore then onwards with those airlines to your destination.
Always sort the long haul leg first (which pretty much describes every plane leaving NZ!)
It’s not difficult, just jump on google flights. That way you can call Air NZ and tell them what you want while everyone else is playing the passive game and waiting to hear back and will end up with leftovers.
I basically dislike the hassle of chasing up a refund and amounts etc. I’m put off just by reading others stories on forums and seeing how long things can take. It would wind me up.
I don’t think I’d take any refunds or reorganise my own flights as closer the time they’re likely to be more expensive which would also irritate me.