The first killer app is already here: decentralized exchange.

The highest volume DEX, Uniswap, had trading volumes that rivaled those of the largest crypto exchanges, like Coinbase Pro and Kraken, over the summer.

It provides a user experience that in many cases is superior to that provided by traditional exchanges, with nothing more than a MetaMask extension on the browser needed to trade Ethereum-based crypto assets, and with no requirement to hand over custody to a trusted third party.