Hi Jean, you might want to add Divi Builder into your list.
Re:Page builders and Gutenberg. My initial reaction was “oh no” page builders are dead. Then I realised that page builders have an advantage because they already have a userbase and have worked through the kinks of what users want from a typical page builder. All the “typical” Gutenberg complaints, the page builder developers have already dealt with and found solutions to it.
The trick, as you say in your post is, how will they morph into something else…
I think it is a Massive opportunity for page builders. Converting all their assets to become Gutenberg blocks. Huge opportunity.
We have built a niche business around Divi with premade custom modules and page templates (page layouts) at WP Den and Divi Den. Page builders should aim to become integrated into Gutenberg Asap and use their experience of what users want and need, to build their user base.
It did not “click” for me until I saw what Atomic Blocks did with their beta launch. When I saw that… I realised the epic opportunity hidden inside of Gutenberg.