I think BTC is a key indicator of the overall market sentiment but it has a lot of its value priced into it right now given where it has come from since its creation. Therefore, other assets with promising projects will tend to outperform when demand and sentiment is positive in the market. So when these overall increases happen BTC dominance will fall like it has recently from 48% to below 37%. This is not a bad thing for BTC either as it cannot be expected to always dominate the market cap forever. Rather, certain projects will dominate in their own space (i.e. ETH in platform and Dash in privacy coins). The market as a whole will continue to move forward.