Will Ethereum be worth more than Bitcoin?

No (in terms of USD)

One simple point people fail to realize is that Bitcoin has become a currency you use to purchase other currencies. Most exchanges are Bitcoin based. This means you need to have Bitcoin to attain a certain currency. Let’s take Bittrex for example. If you decide you want to buy DASH and you only own Ethereum, you’d have to trade your Ethereum for Bitcoin, then trade Bitcoin for DASH. You can’t trade Ethereum for DASH. There are other sites that allow you to trade Ethereum for DASH but the prevalence of Bitcoin as the main trading currency is much more. I am for one am not invested in Bitcoin but I find myself purchasing it all the time to attain other currency. This contributes to growing the volume of Bitcoin and will most certainly be a factor in growing it and keeping it alive for a long time.

Oh and not to mention the circulating supply of Ethereum is much bigger.