At some point altcoins depend on bitcoin. With a probability of 99% in 2019 bitcoin will remain the most reliable and popular coin. Btc determines the market, but during the general tendency of growth, some altcoins might turn out to be even more promising. It is hard if not possible to predict a future leader thats why investors often choose several coins for their portfolio. In my opinion, the process of correction is ending, and the crypto market is at the edge of a rapid growth.