I wasn't expecting the ATH to be overtaken by this year and this is why I'm not surprised with the sliding. Although, it is a kind of correction but I can't say when we are going to see a stop.
Really...
If bitcoin gets to that, what do you think of altcoins 
We've passed the last high, you should be looking for the next bottom. I call between $1k and $2k.
Really...
If bitcoin gets to that, what do you think of altcoins No-one would give you a definite answer as to what is going to happen to any market. Either two things for Bitcoin right now;
1. We have switched to a long term uptrend and right now some little correction which should give us a higher low when the correction completes
2. This is just a bull trap and we could still have more downside. However, this should be glaring based on certain psychological supports leading to a lower low, but a good time to load up more.
As for altcoins, we all know the answer to your question. Some are already dead as at now, more would die and basically for the altcoins with no usefulness, which most of them are, death is inevitable anyway.