I think Auckland will roll on pretty well. If immigrations stops for an extended period the regions will suffer. Rents will drop but only nominally but values could really fall in rural areas where they have exploded unreasonably.

If you document house price inflation since we kept records, property has doubled on average every 7.8 years including through the 2 wars and the depression. NZ is not that expensive in real terms. It is hyped as expensive in relation to wages and that's true but our actual values aren't high compared to many similar markets. This is what makes real estate so low risk. Safe as houses!