National doesn't have a narrative, that's the best bit. It doesn't have to. All it has to do is what it always does in situations like this - shut up and let Labour keep digging.
YES there's a bubble in the Auckland property market. It's caused by a shortage of houses because Auckland's zoning regulations and NIMBY residents won't allow the city to expand upwards or outwards. So the only people who can afford to buy property in Auckland are people who got rich elsewhere or existing homeowners who bought houses when they were cheap and who have leveraged that into multi-property portfolios.
Right now* there's a lot of Chinese money entering favourable real-estate markets all around the Pacific Rim because China has a fuckload of rich people who want to cover their arses in case of government intervention in the Chinese economy. These people (generalising here, etc) tend to gravitate towards business-friendly governments, because working hard and succeeding in business is good, and they fucking hate communism with a passion because China, so they won't go near any political party or movement or person that has ever been in the same room as communism, ever.
Strangely enough 21st-century National does not have a large problem with people who hold such beliefs. Mid-20th-century National would have lost its fucking mind at all this, but that was a different party.
Prediction: National will sit back and let "totally not racist" Labour haemorrhage on this for a while then introduce a new business-friendly Auckland housing policy of some sort - say non-resident/non-citizen buyers can only build new properties, not purchase existing ones, and there won't be any sort of "racial profiling"** built into it, and the Auckland city council will fold in the face of overwhelming pressure and free up land on the fringes, and the construction industry will boom and all that money will flow into the local economy, and there'll be more houses and National saves the day, yaaaaaaaaay.
The usual for Key's National in other words. Let Labour flounder around trying to find something to campaign on, let Labour fuck it all up completely, then identify the bits that could actually work to National's advantage, polish them up, and announce those as National policies.
* when the average Auckland house price increased from 300K to 600K under Labour between 2001 and 2007 that wasn't a problem, but now it's 755K? Holy shit, must be the fucking Chinese!
** the fact that Labour has allowed
these words to be published anywhere near each other is evidence once more of its total incompetence at communicating.