The battery is expected to last 20-30 years (or 10,000 cycles..charges and recharges).
Sorry no sources for this assertion, but I have read this in the past.
I am not ideologically opposed to the sale of the government section of the battery (especially it the proceeds were used to "seed" future storage options)
but my guess is that the function would stay the same.
The computers at Hornsdale monitor the National Electricity Market with intimate knowledge of who is producing how much power and where.
This is what makes the battery so useful in "grid stabilization"...it is like a "big brother" watching the grid, instantly adding power when "fluctuations" occur.
The health of the grid is number one priority, easily more important than power shortfalls in any given area.