While your concerns and analysis is valid, it was the citizens of Australia that allowed this to take place by marching down and turning them in when told to like good little sheeple. And as I feel for the sheeple of Australia, they did bring it on themselves.
Should this happen in the U.S. there will be many that refuse to do such. I being one of them. "It is better to die on your feet, than to live on your knees". I forget who said it.
My wife once asked me what Iwould do if this came to pass in the U.S. I replied, "Nothing". See asked what I meant. I told her that I would definitely NOT turn my guns in. She then asked what I would do if they came to confiscate them. I told herit would be her decision that mattered, not mine. She asked what I meant by her decision. I told her she would need to decide if she was going leave and live or stay and load.