I don't think the other cryptocurrencies will take a hit in the long term. Short term, there could certainly be a bit of step back. However, there could be quite the opposite effect as well and we have seen this one over and over again in the cryptocurrency market. As bitcoin declines, the altcoins have inversely risen. I believe that would be the most likely outcome of a bitcoin decline. People seem to be catching on to the idea of a digital currency, so I think that thought will remain.
RE: 2018 - The Year Of The Altcoin