Reopen borders (with appropriate controls) with other countries that have no cases. NZ is in talks with Australia to figure out what the right border controls will be. There are some obvious Pacific Island candidates too. And then Taiwan, South Korea, Singapore, and so on.

I think the world's bifurcating into two blocs and there's a Viral Curtain between them. Within each bloc it makes sense that there can be free movement -- if you've given up hopes of eradicating it, then you have nothing to lose by visiting another country.

Infected people coming into a virus-free zone are a clear and present danger and will require tests and quarantine. This is what happened for the cast and crew of the Avatar sequels, who recently re-entered New Zealand to finish filming. They were tested at the border and are in hotels for a period of managed isolation.

The end-game is a vaccine, which lets us intermingle without unchecked exponential growth.