Yes.

Since RN is using 16 for a while now, they already did, or am I wrong?

If I'm not mistaken, https://github.com/facebook/react-native/commit/b58207e61fcb... enables the new implementation in RN. So it'll be in React Native 0.49.

The "react" package is mostly irrelevant here since it only contains a few utilities. The actual reconciler is synced separately, and no, it isn't enabled in RN yet (but maybe will be in the next stable release).

Do RN projects just need to upgrade React then?

No. We'll update RN with the new reconciler in the next few versions.

Don't expect it to magically improve performance though. But the async stuff mentioned in the post will definitely come to RN when it is ready.