In reply to chuck.

I'd tend to agree considering there's little to be done in regards to the additional WP editor experience fragmentation that Gutenberg will create anyhow.

I see WP development falling into 3 categories (at least)...

1) Become aware of whether you're running on a system with the old TinyMCE or new Gutenberg and act accordingly. If it's a plugin that can dynamically alter this fact, that further complicates things but only slightly.

2) Offer separate v4.x and v5.0 versions.

3) Stop development of the older v4.x branch versions and only develop v5.x going forward even at the expense of lost users.