Essentially the plan is to maintain a policy of elimination/zero community covid while gradually opening up and allowing people coming into the country to self-isolate at home rather than in managed isolation hotels.
That's really not going to work, and it's a bit reminiscent of the way JA keeps blowing hot and cold with Five Eyes-saying she wants to be part of the alliance, while also trying to remain friendly with China. In 2021, that kind of policy isn't going to work any more-NZ needs to pick a side (the Five Eyes side, hopefully).
With COVID, there's a need for clear and honest messaging here. If they want to open up borders, they will need to accept spread of the virus. COVID isn't going anywhere.
And as we have seen in HK, Australia and other countries, if governments refuse to be honest with their electorates and spell out that COVID IS COMING, LIKE IT OR NOT. GET READY OR GET SICK, then a lot of people will decide that since they can afford to be awfully fussy about vaccines, "wait and see," "Why should I get vaccinated it looks like there's going to be next-to-no COVID in the country anyway?" etc.
It seems like NZ is hoping it will be able to treat COVID like measles--"we can keep community spread out and quickly crush any outbreaks that occur." But COVID isn't anything like measles, and is far harder to eliminate.