It will be very difficult to dump the market further(it is possible, but it will be very difficult and dangerous), because the miners are already working at a loss on some coins, like ethereum. Bitcoin almost fell to mining cost price, so, i think, it worth to start to buy now.
Well, now it is difficult to say what will happen to Ethereum , I think many miners are working in the negative, but with the approach of the update, I think many will on the contrary buy this coin to keep in the long