Depending on the reason for its crash. If it's something that generally affects other cryptocurrencies it will definitely affect other coins but if it's bitcoin specific problem I doubt it will have major impact on other coins.
If bitcoin will crash then all coins also crash because this technology only bitcoin they supported towards a replacement of fiat in the future .All coins are depended in one market which is BTC as you look they are all on trend .
Some interesting thoughts on this forum. Suppose there was negative information about Bitcoin, there was a big panic, Bitcoin devalued, collapsed. Yes, for some time there will be confusion in the market. However, then everything will settle down and line up in a new system. Now each cryptocurrency is able to work independently. The choice of the exchange mechanism, the selection of pairs, these are already technical details. This, of course, is simplistic, but I see no reason for the market to disappear in this case.