In reply to Justin Tadlock.

Cheers Justin...

I won't look to perpetuate the discussion here and wait for your new post...but I leave you with this thought...navigation containers and sidebars (a.k.a Widget Areas) appear to fulfill the same function in a post-Gutenberg world...to contain blocks in a fixed area of the page. A number of legacy themes have supported Widget areas in Headers and Footers. A Navigation widget was common. So this is not a radical new idea I am floating.

I accept your comment that this is a change to the HTML that theme authors are used to...but...come one...as a theme designer myself I can safely say that horse has left the paddock when it comes to maintaining pre-Gutenberg coding conventions ;-) I'm not sure why widgets / sidebars, of all things...would be a legacy metaphor that is retained moving forward. For my part I have moved all my legacy theme code into a plug-in and assume it is all dead code. I am starting fresh with a blank theme canvas that assumes it is a thin veneer on the core Gutenberg functionality.

Other than retaining a "legacy widget container block" I would be disappointed if there was not a new Gutenberg version of the "widget area" (Fixed Group Block!) within which everything is a block (including block wrappered legacy widgets...however that would look).

I look forward to your new post. I enjoy your writing immensely...you are an excellent writer with excellent WordPress knowledge and design ideas. A pleasure to follow :-)