The caveat being the South Australia has a power grid that is sometimes a contender for the worst managed (and most expensive) electricity grid globally. Or at least highly challenging to get it working smoothly.
So the battery is a huge success story and we'll see more like it - but the conditions where it succeeded are not necessarily where the gird wants to be.
That's a strong claim. Wholesale electricity prices in South Australia are currently around USD$45/MWh.
My understanding is that South Australia has historically always had the highest electricity prices in Australia due to dependence on gas generation within a small market controlled by two players who took advantage of their market power, but that this is starting to reverse now due to the shift to more renewables over the last decade, and South Australia may now be on track to have the cheapest electricity in Australia.