I’ve been working on coming up with a plan to re-write a word vsto as an addin using office-js. Several of the key features would rely on functionality that’s only available in the preview api.
I’m trying to decide whether it’s time to start implementing and waiting for the production release.
Is there any idea of when the current preview features might be ready for use in production?
The development process takes time, so you could get in time with a new release.
There is no publicly available dates for releases. But I'd recommend attending community calls where MS representatives can answer such questions.