I thought that too: but Jacinda was flat-out asked that as a question and she basically rejected it. Even with countries that "contain it" like Singapore/NZ, neither of them are willing to treat the other as "clean" - they would still need some form of testing. My guess though is that it'll be a dual-thing. Like you said, there will be a "travel block" of contained countries over on this side of the planet (likely NZ/China/Singapore/other SEA countries/Australia, although Australia seems less keen to join in) AND you'll also need some form of rapid testing. Outside of the USA developing it, I haven't heard any news of it being studied/developed, unfortunately. Hopefully the Chinese government is looking into solutions for it too so they can resume international travel.