If you have the means to do so I think this could be a very good trade. Selling BTC to by AU and then do the same in reverse. From what I can see they are polar opposites. I would keep a core position of both if you wanted to do this and then use a small percentage to swing back and forth. You may not get "rich" from this but it could protect some of your profits from being wiped out in this crazy BTC sell off. Its like boarding up your house before a hurricane, it will not prevent all damage but at least you will have enough left to rebuild.