I think that the rise of mainstream currencies are always signals of positive movements of altcoins in the future .All altcoins follow Bitcoins global trends. It happens because if people see that BTC is falling and a bear market is soon, they sell off altcoins first, as they are more risky. So we often observe that when there is a severe crash of BTC, all other coins also fall.
The global market will depend on the trend of bitcoin movement, someone will predict that altcoins will go up if the bitcoin market analysis shows a strong signal indication towards an increase, without the support of an increase bitcoin will hamper other altcoin markets, for example the case in last May when the market was bearish even only altcoins fill the list of gainers with the lowest declines.