Hydro is the best, but there are no new locations with the right topography in Australia to build them. In fact, there aren't that many new places in the Western world left where they could be built. (Still a lot that could be built elsewhere.)
Battery farms might become more viable if the price continues to drop. That would be a game changer for both solar and wind energy. In Aust, there are already household battery storage units being sold to compliment solar units, but that says more about the exorbitant electricity prices from the grid, than whether batteries are economically viable. A more traditional alternative to battery storage would be something like the Dinorwig pumped storage scheme, but there are probably no suitable sites. Even without storage, solar is a part of the solution, and each state now has a significant proportion of its electricity from solar.
Personally, I think the long term answers are nuclear (reliable base load power), and biofuels (for transport). Both are obviously controversial.