Besides Bitcoin, during the past week, we saw Etherum also dip seriously against the dollar, breaking previous supports and moving as low as 530; Is this just Etherum making a correction or should we expect more moves to the downside. HODL or Sell?? 
We are over the course of correction only. Last year prices were hiked to the hottest peaks ever but that was unexpected hike or many says that it was perfect stepped up manipulation that was done earlier. This led the market to receive out of the box volume which it wasn't supposed to get in first place but it did.
This happened with all the crypto currencies and thus now they all are getting corrected to the right prices. For ETH 400-500 USD has always been base price and thus I dont think it will drop beyond this rates.