I don't agree because ethereum going downward trend and bitcoin going upward trend ethereum will fail once lots of ICO happening based on erc 20 token proves scam.
Even though everything is possible and no one know about the future, but I think there is a big gap between the two. Bitcoin price is so much high as compare to Etherium, secondly the popularity of bitcoin is also increasing too and thirdly the users of bitcoin are also more that the popularity of Etherium and if this trend will continue the i do not think that Etherium can fail bitcoin.