It's not really fair to say that there's no chance of getting rid of cats in NZ, might be more accurate to say it's not something that will happen soon. As you

It's not really fair to say that there's no chance of getting rid of cats in NZ, might be more accurate to say it's not something that will happen soon. As you point out, a good step would be to require cat registration, and in some areas that has very nearly become a reality in recent elections. I'm not a conservation expert, but think it's safe to say that the answer to your question is a bit complicated. We have a national goal to be free of a list of predators including those by 2050 - it seems achievable, but only with a lot of work and political willpower. Stoats for instance can be killed with traps that cats can't get in to, so that's a useful tool in the more accessible areas where we still have pet cats to contend with. One of the more immediate issues in the big picture, is a small but vocal faction that's violently opposed to using a poison that is key in these efforts. To give some flavour, check out this recent and very well-done series: https://www.rnz.co.nz/programmes/fight-for-the-wild https://www.rnz.co.nz/programmes/fight-for-the-wild