In reply to Matías.

Was there not already an attempt to "augment" this on the server side earlier? I may be misremembering this. Nevertheless, I do wonder if that is an ideal approach. I suppose you could check for a heading and following content and wrap them. However, that seems tough to get right and full of edge cases.

I'm a fan of wiping the slate clean and starting over by having an opt-in "block areas" feature for theme authors that is independent of the old sidebars/widgets system. Right now, if I am reading the code correctly, Gutenberg is essentially creating a widget that houses blocks and outputs them on the front end -- literally square peg, round hole. This should be so much simpler and not create technical debt for a brand new feature. Do not try to fit the new block area system into the old sidebar system.

The new system will seem forced, particularly because (at least right now) it requires that theme authors opt out if they are not ready. Let them start using a new and exciting feature at their own pace.

I am guessing the idea is that the team wants to ship new features to as many users as possible. This requires putting a new thing inside of an old thing. But, I think you can lean on the plugin/theme development community to do this right.

Also, thanks for the feedback on making patterns available to the "widgets" area. That will be helpful.