The problem with new editor is - it is too much simplified - similar to medium yet confusing to use.
The editor is like what start menu was for Windows 8. In my opinion, the massive change and UX/UI issue seem to be the major problem with adaptability with Gutenberg.
Change UI to make border much visible and make user know they can add “blocks”. Probably a startup explanation about blocks? eg.

Currently “Insert” menu is dropdown menu which displays various blocks options and elements. Rather than showing them in dropdown they can be added at the top as a toolbar. There are already lots of whitespaces.
Just change TinyMCE with the new editor! No other interference with theme, plugins, meta box etc. Just change current tinymce editor like most of visual editors do (eg. Divi, SiteOrgin).

_Note: This is quick mockup!_
Intriguing idea!
Maybe best one I have seen in all this "believe", "imagine", "hope" Gutenberg confusion.
leave everything as it is and replace (remove) just TinyMce block with Gutenberg. Possibly change design after wishes. And use Gutenberg (take over screen) in distraction free, fullscreen mode, as optional option, for those who want it that way.
Why they cannot admit they rushed it with React ? Now when we know Facebook does not step back regarding its licence.
First, it's great to see explorations so thank you @pritush for taking the time on this. I have to admit seeing the somewhat merged UI, I do think there is a danger of causing issues just by doing that. A few things though to pull out I think worth considering.
I feel it's worth maybe pulling things out as there's a lot you're commenting on in one post. However I would be keen for the discussion to continue around what should a block feel like. Lets keep this about the UI not about the framework as that doesn't matter in this case.
I do like the first look of having something a bit stronger at the bottom of a block. At the moment, we've got a bit of trouble discovering how to insert a new block between existing blocks, and I keep feeling that some kind of block footer is needed to start solving that.
I am closing as we need to pull out anything into actionables over have a general issue for this.
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First, it's great to see explorations so thank you @pritush for taking the time on this. I have to admit seeing the somewhat merged UI, I do think there is a danger of causing issues just by doing that. A few things though to pull out I think worth considering.
I feel it's worth maybe pulling things out as there's a lot you're commenting on in one post. However I would be keen for the discussion to continue around what should a block feel like. Lets keep this about the UI not about the framework as that doesn't matter in this case.