Correct, the bail in laws have been in place for some time but it would be a brave or a gov't with no other options to allow a bank to take deposit holders funds. If a "major" Aust bank got into trouble, the gov't would mops likely relax the "4 Pillars" rule and find that bank a dance partner to prop them up (and maybe some gov't funding too)... same as what happened in Japan 15-20 years ago.
As for the Aust Gov't deposit guarantee, unless they have changed the rules (haven't looked at them for a few years), if you read the fine print, the Gov't will only cover deposits once the bank has been liquidated and monies paid to secured lenders and deposit holders. The Gov't will then pay any difference between what the deposit holder rec'd from the liquidator and any short fall up to what they had up to AUD250k each person per bank. In short, you can't rock up to the RBA and ask to be paid day 1 of a bank failure. Note: Liquidations of companies take time.... years...... go look at how long Annett and the HIH liquidations took and then then think how long a major Aust bank liquidation would take.... unwinding their derivative positions and arriving at a numbers would take years.
Remember and it's been stated here in this forum before, the contents of safety deposit boxes in a bank can be claimed by a liquidator... so don't keep any PM's or other valuables in a bank safety depot box.