When I first heard about the Predator-Free 2050 I rolled my eyes, because it was proposed by the prime minister who tried to change the country's awful flag when polls showed Kiwis inexplicably liked it, and because he didn't actually increase funding for controlling invasive species.
However this article is interesting, because it suggests that it might be possible to eradicate rats, stoats, and possums from New Zealand with CRISPR. He basically says:
With Crispr, you can implant gene-drives which will drive damaging drives throughout a population.
BUT it would be really hard to keep some asshole from smuggling rats out and eradicating rats across the world.
BUT you could engineer rats which have severe peanut allergies and then feed them peanut butter.
BUT someone who wanted to eradicate rats locally could still smuggle them out, and then the world would have GMO rats which people wouldn't like.
Honestly, I think that the anti-CRISPR objections are far weaker than than the arguments for it. The "Oh noes countries will be upset at the existence of GMO rats" argument is just ridiculous. It's true, but it doesn't mean we have to accommodate left-wing anti-science hysteria.
However even a gene drive that would eradicate all of the rats wouldn't be a problem. Many endangered species reproduce and mature slowly and suffer from population bottlenecks, many of them are expensive to care for. If someone introduced an anti-rat gene, there would be plenty of time to gather up a large and diverse population of un-CRISPRed rats, and it would be easy and cheap to maintain them by captive breeding until the problem passed, then re-released into the wild.
But this assumes that even gene drive rats could compete on a global scale. The article notes that rats have trouble getting established where there are other rats. If there's an area which can't support many rats, it seems not unlikely that the CRISPR-edited rats will die off on one side of it, and unedited rats will reinvade.
I'm cautiously optimistic. I sincerely hope that this works, people freak out about it less, and we then see rabbits and foxes eradicated from Australia, starlings extirpated from North America, and eastern gray squirrels eliminated from California and Europe in my lifetime. (Actually, I'd like to see eastern gray squirrels eradicated in their native range too, but somehow I feel like that will never pass muster.)