Tiwai Point shutting up shop

[nzoomed]

IDK, it could still supply most of the south island anyway. Im not sure how much capacity the HVDC link up to the north island has, but I know it has been upgraded with a new cable across the strait, and the old cable probably could still be used if they wanted.

This would seem to be the inside info from Transpower. Long story short, completion by Winter 2023:
https://www.transpower.co.nz/news/transpower-seeks-input-clutha-upper-waitaki-lines-project

Looks like at least they were planning for it.
Im not sure if the power station really even feeds much of the grid, I think they could link it up if they needed to, but pretty much all the transmission lines run from lake Manapouri straight to Tiwai point.