Ethereum, being the world's second largest cryptocurrency by market cap, has all the potential of replacing Bitcoin in the future. It's more than just a cryptocurrency, being a platform for the development and execution of smart contracts (aka dApps). With ETH, it's possible to launch alternative cryptocurrencies without the need to start a Blockchain from scratch. It's also possible to use the ETH blockchain for other purposes such as voting, proof of identity, verification of documents, and more. In contrast, Bitcoin's only use is for finance where it cannot be implemented in other areas by its own.
Given all of the benefits Ethereum provides on top of Bitcoin, it makes me wonder whenever it'll be able to replace the pioneer cryptocurrency within the future? As long as, Ethereum keeps progressing in development and mainstream acceptance, it'll be much closer to Bitcoin every step of the way. What are your thoughts?

We will be dependents to the big investors with regards to the future of ethereum as they are the source of demand and once the demand of ethereum will surge then it will surely replace bitcoin.
But right now big whales are favoring bitcoin so the chances to replace bitcoin in the next five years is very difficult, let's just hope that they will change their mind as soon as possible as I saw also the potential of ethereum.