Linuxluver:
It's just more sprawl. Not a solution even in the short term.....never mind the long term.
Provided some jobs and services can be made local to the new town, it's a perfectly good solution. If you look at the original garden cities in the UK, they are now quite balanced, not just commuter dormitories.
We're not short of land and we don't all want to live in city apartments - a bit more diversification and expansion from Auckland would be a great thing for NZ. There are plenty of mega-dense mega-cities with fantastic public transport if that's what floats your boat.