Tiwai Point shutting up shop

[harm_less]

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.

From Wikipedia: "Manapōuri is connected to the rest of the National Grid via two double-circuit 220 kV transmission lines. One line connects Manapōuri to Tiwai Point via North Makarewa substation, north of Invercargill, while the other line connects Manapōuri to Invercargill substation, with one circuit also connecting to North Makarewa substation. Another double-circuit 220 kV line connects Invercargill to Tiwai Point."