ETH is related for me it's pretty obvious that some whales have been involved in the BTC crash. They just profited from the bitfinex incident to use this sell off traction while pumping ETH. This makes BTC holders to psychologically see ETH as a place to be while BTC corrects. Dont fall for it.
What if it's a double bluff?
If you are here for the long term it's worth risking buying at whatever price (500, 600 or 700) it doesn't matter. In the long term you will end up with more money than you would by trying to profit from shorting BTC against USD or against other altcoins.