Uhm, 5% of national output is a lot of energy. That's not relatively bad or anything, but improvements in transmission would be like getting power plants for free.
High-temperature superconductors: I want to believe.
The Snowy Mountain scheme is around 1500km from Adelaide. It might help in the Eastern States, but transmission losses are significant over that distance, and in the Eastern States they haven't had the power problems yet.
I already said battery switches faster. You are simply repeating what I said.