I think the best we could hope for would be a dedicated battery manufacturing plant - we have all the natural resources here, and unlike EVs, the market for home batteries and grid scale battery systems is huge here.
While unlikely, it could theoretically also act as a sort of "final assembly" plant for vehicles, where vehicles made elsewhere are shipped to Australia and have their Australian made batteries installed. Sort of like Tilburg in the Netherlands (although in that case, it was for EU tariff reasons - this would be purely logistical). This is less likely, however, as they move to structural battery packs.
My other thought - Mike isn't stupid, he might know things we don't and is making this public statement in order to elicit public statements from certain people - politicians, etc.