Great article! For anybody interested in this topic, I've been working on a schema migration tool which automates zero-downtime migrations using many of the techniques mentioned: https://github.com/fabianlindfors/reshape. It also uses some other incredible Postgres features, like updatable views and schemas.
Promising and innovative tool indeed. I wonder why the big PG users and players are not investing in this (potentially) game changer tool. (AWS, zalando, gitlab, yugabyte, edb to name a few). Great work!!
It was discussed here on HN about a week back: https://news.ycombinator.com/item?id=29825520