Yea, this is something I've been pondering. Not because I'm currently concerned about the viability of Australian banks, but because I'm concerned about the panic mentally of the Sheeple.
If one major commercial bank fails, the Sheeple are too ignorant to discern the difference between commercial and retail banking, and that may start a run on cash.
Am I currently concerned that the banks will fail, in Australia, no. But I predominantly only use cash now, so not being able to access any would be very inconvenient for me. With that said, I have always kept enough in my account to cover a minimum of 3 months of automated payments, and will continue to do so.