Ethereum has been published since 2014, since that time it has accompany Bitcoin as crypto currencies coins which has many supporters and market participants interested in investing in it. As the progress of Crypto currencies was rapid, there are more coins created after such as LTC, Ripple, Stellar, etc. I think Ethereum can challenging Bitcoin as soon, but the fact this coin also has many competitors of its own, so in my opinion Ethereum not yet able to pass Bitcoin but still be top of altcoin other.