An important part of Auckland's plan, therefore, is that the rest of New Zealand will become relatively more attractive to live in, and/or net migration will slow and/or the birth rate will slow.
Even if those things do happen, we'll still struggle to cope.
The second challenge is to share the prosperity. The plan contains some stark figures. In Devonport-Takapuna, Upper Harbour (Westgate to Albany) and Orakei almost no one falls into the "high-deprivation" brackets. In Māngere-Ōtāhuhu and Otara-Papatoetoe, almost everyone does.
"This is a major issue," says the plan. It talks about the impact of deprivation "across broad ethnic and age groups" and sets out some strategies for change.
In an intriguing section, the report identifies several "possible futures". In one, the city becomes a "food bowl": "we farm on kerbsides, in pocket parks and backyards ... [while] flat roofs and old industrial buildings in Penrose are transformed into soil-free gardens." In another, we are a "safe haven" for refugees from climate change.
In a third, though, disparity has "stubbornly remained". The city becomes divided by the north-south motorway, unemployment doubles and town centres from Albany through Birkenhead, New Lynn, Onehunga and Manukau are all blighted.
The third challenge is to reduce environmental degradation. The plan identifies two major barriers to this: urban development, where pressure is already growing to build quickly and damn the consequences, and climate change.
The plan is full of numbers and lists. After those three "key challenges" come six "outcomes", with a development strategy laid over them, and 32 ways to measure progress. There'll be a "report card" each year and a "progress report" every three years. Data will be updated on a rolling basis. The Herald will keep readers posted.
There's also a glossary of 159 terms, a kind of handy guide to the contemporary intersection of economics, sociology, officialese and Te Reo: kaitiakitanga, strength-based models, elite soils, papakāinga, sense of place.
At the council meeting yesterday, Deputy Mayor Bill Cashmore called the plan a "matrix of information with detail in each section not siloed but cross-linked". It's been put together as a digital document, so if you want to follow the impact of each proposal on your own ward, or discover the relationship of light rail to employment, shopping and environmental impacts, you can follow the links.
You can't do it yet, though: they're still fine tuning and will have it online sometime in July.
The consultation process generated more than 18,700 written submissions and 5000 people turned up to feedback events. Cr Darby told the council that "over 300 material changes" were made as a result of that feedback.
Cr Cathy Casey, often a critic at the council table, was enthusiastic. "We've had some epic battles, with blood, sweat and tears," she said, "but I think what we've got reflects what I'd like to see Auckland become."
She also said "the consultation has been great". Crs John Watson and Wayne Walker voted against, with Watson saying there had been "no consultation". Cr Mike Lee, also against, called the plan "not logical" and said it "may even be illegal". Cr Greg Sayers wanted affordable housing to be the only priority so he voted no as well.
Auckland: towards 2050
• Population growth will be biggest in Rodney, Franklin and Upper Harbour. Waitakere and Manurewa will hardly grow at all.
• Big new parks will be needed in Warkworth, Kumeu and Pukekohe. Regional park expansion will be needed on the coastline at Pakiri, Mahurangi and Manukau.
• Nearly 40% of all "advanced sector" jobs (knowledge-based industries and high-tech manufacturing) are in the city centre. Another 12% are in the Maungakiekie-East Tamaki area.
• In the most recent council election 58% of people in Waiheke (and 69% on Great Barrier) voted, but only 28% in Manurewa. In isthmus Auckland and north of the bridge, voter turnout was a bit over 40%; in the west and east it was around 35% and in the south 30%.