Given that the Auckland transport system can barely cope with the existing population, it's a little difficult to imagine quite how it would cope with more than five times as many daily travellers. There'd have to be huge investment in rail transport, a metro, a couple of new harbour crossings, possibly a second airport somewhere, not to mention hundreds of kilometres of new motorways ...
Would the new migrants really generate enough extra income to pay for infrastructure on this massive scale? Certainly not until after they'd got here, and the whole place had already ground to a complete standstill.
It's not just transport, of course: water supplies, sewage, electricity - they'd all require vast injections of cash. Wouldn't we need a big new power station (somewhere, operating on something)? And then there'd be the new schools and other public services.
Access to the parks and beaches would have a very different character. I can imagine a dual carriageway to Piha, with multi-storey carparks charging $10 a day. At Long Bay, you'd be shoulder to shoulder on the beach - if you could get there.
For the nouveaux riches, of course, everything would be fine. They'd be able to afford chunks of pristine land way out of town for their weekend residences. A handful of farmers would do very well selling off large areas of land for exclusive golf courses and country estates.
Meanwhile, back in town, the whole metropolis disappears in a cloud of smog.
Fanciful scaremongering? Well, I have at least tried to envisage how it would all pan out. How do the enthusiasts for a large population see it working on the ground, so to speak?
It's sometimes suggested that a larger Auckland would be a livelier and more cosmopolitan place in which to live. But isn't it already lively and cosmopolitan?
If it's not cosmopolitan enough, or insufficiently bustling, may I suggest that, instead of trying to transform it to suit their preferences, the high-population enthusiasts decamp, say, to Sao Paulo or Shanghai, which would surely meet all their expectations, and leave this dreary, lifeless, impoverished place to those who prefer it more as it is?