It could happen but for the time being, we should concentrate on Bitcoin, Bitcoin first then others will follow, when majority of the people in the world are now using Bitcoin, we can think of a better alternative, it could not be Ethereum right away, there's a lot of new coin coming or coins now that are now improving.
Well, Bitcoin's the one cryptocurrency which started this movement after all. Other cryptos that came before Bitcoin are called altcoins and Ethereum is one of them. No matter how innovative and actively developed Ethereum is, I don't think it would be able to overcome the original cryptocurrency anytime soon. Right now, its market cap is way below Bitcoin's. Not to mention, the total supply of ETH is undefined. This would prevent Ethereum from becoming a store of value in the future. Because of this and many other reasons, I believe that Bitcoin will retain its rightful place on the market for quite a long time.
We should focus on Bitcoin first, since it's the biggest cryptocurrency in the world. Then, we could focus on other cryptocurrencies which are meant to be a complement to Bitcoin in every way. Ethereum, Litecoin, and many of the other cryptocurrencies on the market have their unique features and uses within the mainstream world. Ethereum's smart contract capabilities provide an extension of features within the Blockchain. This proves that Bitcoin's technology is far more capable of fulfilling other industries in the mainstream world than we've ever thought before. With due time, ETH will be able to grow into an unstoppable platform for decentralized applications while Bitcoin remains as the world's most trusted store of value.
Nonetheless, there's still the possibility of Ethereum replacing Bitcoin in the future if the latter doesn't improve in terms of scalability. Since crypto is known to be extremely unpredictable, anything could happen in the future. Just my thoughts
