I don't think that Etherium will ever manage to bitcoin as cryptocurrency No. 1 because all of us know that the Bitcoin has much more users and investors in comparison with Etherium which is younger. Always was in all news that the bitcoin is on continuous increase in its market value, despite some time when its market value falls. He always seeks to rise again, covering your losses and acquiring profit.
Yes i agree with you, bitcoin is the king of cryptocurrencies and however ethereum is just copy cat of bitcoin with some new feature are like smart contract and decentralize application (dapps) of course include scaling and security problem too. 
if we know ethereum be used for payment on the most ICO but doesn't mean it will overtake the bitcoin.