This blog post tracks actual and potential features of ES2020. I will continually update it.
Note that since the TC39 process was instituted, the importance of ECMAScript versions has much decreased. What really matters now is what stage a proposed feature is in: Once it has reached stage 4, it can be used safely. But even then, you still have to check if your engines of choice support it.
Promise.allSettled(Jason Williams, Robert Pamely, Mathias Bynens)
for-inmechanics (Kevin Gibbons) [proposal]
export * as ns from "mod";
The following features are currently at stage 3:
String.prototype.replaceAll(Peter Marshall, Jakob Gruber, Mathias Bynens)
Promise.any(Mathias Bynens, Kevin Gibbons, Sergey Rubanov)
Atomics.waitAsync(Lars Hansen) [proposal]
If you are wondering what stages various proposed features are in, consult the readme of the ECMA-262 GitHub repository.
Yes, the TC39 repo lists finished proposals and mentions in which ECMAScript versions they are introduced.