After large ES6 release, that took about 6 years (Dec 2009 — Jun 2015) to get standardized, TC39 committee has given notice of annual but smaller releases, starting with ECMAScript 2016 (ES7). The final feature set of ES8 hasn’t been approved yet, as on Feb 2017, though we can suppose that all the specs from stage 4 and most of the stage 3 will be included in ES2017. The proposed feature set appears as follows:
Shared memory and atomics or Shared Array Buffers serve as a low-level building block for top-level concurrency abstractions. They enable developers to share the bytes of SharedArrayBuffer object between several workers and the core thread. Such approach allows you to share data faster, as well as improve and streamline coordination between workers.
That is more or less the most interesting features for the ECMAScript 2017 and it is not finalized yet. There are more features that are worth your attention because so far they are in stage 3 and can be included in ES8 as well: