In my oponion BTC will take the lead within 2 to 3years or more but we can not tell if ETH can still lead BTC. But still possible!!! Just keep track of what happen to BTC and ETH but hoping BTC will stay strong rather than ETH.
As what the coin market cap today shows the big difference between bitcoin and ethereum, the ethereum to overtake bitcoin scenario is very far to happen. Bitcoin had already in the peak and even the ethereum is the next level to bitcoin, still the differences of its market value are still huge that needs for the ethereum to strive harder to reach the value of bitcoin.