well, they no longer produce the "display-only" Chromecast in favor of their "Google TV" sticks with Remote etc. Not that much of a shock here, the market moved on from simple wireless display dongles. Unfortunately no sign of Google Cast protocol being opened for general purpose use. Would be great to be able to run your own custom Receiver-device without needing a Google certificate...
miracast is a decent standard. i'm not sure why we'd need chromecast's proprietary equivalent as well. the fact that google dropped it from stock android kind of says it all - they clearly think that chromecast isn't good enough to compete without being coddled.
Cast and Airplay makes the device itself fetch and play content, with local control and importantly much better display and video manage.
(AirPlay and Cast both support screen sharing, but that is not the main use case.)