Ethereum replacing bitcoin might not too happen too soon. Bitcoin had gone too far and it is considered as the main currency when speaking of crypto. It is the first crypto to be successful and to grow over thousands times compared it's original price when it was created.
Ethereum will never replace bitcoin they don't have the same purpose. I think people who think ripple will grow are late investors who have bought it on great 2017. pump and didn't sell it on time, I don't think ripple has good future while ethereum will grow because of coin offerings. Binance and projects collecting money there will have big impact on ethereum price.