Re: If the BTC crash, will it take every other coin with it?
Of course, first it will affect the whole crypto market, the quotes of all the cryptocurrencies will go down. However, promising coins, which have a real use, such as Ether or Neo, will be restored, and perhaps they will get the first place, and bitcoin will be forgotten. But it is unlikeky happen soon 
I agree with your opinion. This will affect the market. But the market has a lot of coins. If bitcoin disappears, another coin will be king. Because now can not do without encryption technology.