I agree with so many of the comments above, especially @Amir's point about the Gutenberg roadmap feeling pretty condensed.

I'm all for moving things forward, but there's clearly a lot of concern in the WordPress community about things breaking, and allowing time for developers to learn and make their necessary changes.

It's reassuring to hear a legacy editor will be available and I'm eager to know more how this will work. That would calm a lot people! Personally, a default "legacy mode" on all my websites will be my preferred option, then opt-in to Gutenberg.

I don't think it's any exaggeration to say if the release isn't well managed, we could see millions of broken websites and a huge dent in the reputation of WordPress. But I have confidence that won't happen - it can't!