Unfortunately alcony not strong enough designs to be an independent means of payment. The flagship of the entire crypto market to this day remains Bitcoin. And if the rate of bitcoin begins to fall, it entails a decline in interest in all altcoins, and their price also falls.
As far as I know the prices of all altcoins are related to the price of bitcoin, if the king of cryptocurrency begins to fall eventually the altcoins will be down also. But I believe this coming 2019 cryptocurrency will be more stronger.