There has never been a way to remotely play media on an Amazon Echo speaker or third-party Alexa device, at least in the same way that can be done on Chromecasts. Amazon today introduced 'Alexa Cast,' a new feature that aims to solve this problem - but it's only in one app right now.
Starting today, the Amazon Music app for Android and iOS can cast music to any Alexa-enabled device. That includes Echo speakers, third-party Alexa products, and even some Amazon Fire models. The company isn't saying what apps will get Alexa Cast next, or when a public API will be available. "We’ll continue to improve this feature and expand support over time," an Amazon spokesperson told The Verge.