I went as far as writing my own formatter which consumes the db/schema.rb generated string and outputs another string with better formatting. The code is kinda shaky because I wrote it in a rush, but if anyone is interested I can share it with them.
edit: r/care/mind
Also, yarn is way faster.
I think there's now too much going on and too few people reading /newest for the HN front page to be a resaonably accurate representation of the big stories if a key Rails release didn't even make it at the time :) Seen quite a few similar instances as well. (The real issue IMHO is not enough exposure of or encouragement to visit /newest, so it's pot luck if links get seen.)
The new form_with looks convenient. It was always annoying occasionally having to switch all the methods out when a form gets more complex.
I don't really use frontend Javascript stuff, but mostly because it was a pain getting it to work with Rails and doesn't provide much benefit. Maybe in another year the Webpack changes will have made it worth using.
"System tests" look great, too. It's great that they've brought this in as a convention, since every Rails project I've worked on has configured capybara for integration tests.