Sales conducted on-chain through smart contracts couldn't really be done before Ethereum, which is why they are a newer concept. I think this style will become the most common over time.

Ethereum will be a first-class citizen on Coinbase.

Make no mistake - Ethereum would never have existed without Bitcoin as a forerunner. That said, I think Ethereum is ahead of Bitcoin in many ways and represents the bleeding edge of digital currency.

There is nothing that Bitcoin can do which Ethereum can't. While Ethereum is less battle-tested, it is moving faster, has better leadership, and has more developer mindshare.

Ethereum has taken what was a four-function calculator of a programming language in Bitcoin and turned it into a full-fledged computer.

Bitcoin is valuable as a currency because of the economic efficiencies the bitcoin network is already creating as transactions flow over it. As with the Internet, more applications will flourish which will make the bitcoin network, and thus bitcoin as a currency, valuable.