It is possible that this will happen sometime. And when that day comes, what will it change for you? I believe that there is no problem for a trader that the price of altcoins is correlated with the price of bitcoin. This makes it possible to predict the price movement of altcoins by observing the price of BTC.
Only whales can manage to manipulate the market so easily but we have to be ready in case this will going to happen. Doing some TA will help to determine what would be the market's next move.