> WA could be part of the NEM with some HVDC across the Nullabor, not sure if it would be economically worthwhile though.

Part of the motive of moving the WEM to 5 minute intervals was to eventually leave this option open.

The largest renewable project in the world is being planned in this area[0] so it's feasible that it all may be connected one day

[0] https://wgeh.com.au/overview/