One thig to keep in mind about Kidston is that a new high-voltage link to the QLD grid will be built to replace the existing link that was in place for the gold mine. Not sure whether other wind and solar projects could connect to this link - may be too far north.
Syncons are old technology designed for current grid where frequency control is used to manage power fluctuations. In the future grids willl likely change to be managed by voltage control by grid-forming inverters rather than frequency control by fossil-fuel power stations and syncons. In the meantime it's syncons and transmission capacity (and big batteries but don't tell the Prime Minister ).