There are specific steps Bluesky could take to decentralize the network. These are going to sound extreme but I agree with the article that it will never decentralize on its own. (Nothing will ever decentralize on its own so this isn't a criticism of Bluesky specifically.)
1. Strongly encourage backups.
2. Force users to migrate off the "official" PDS until it has less than, say, 40% market share.
3. Make the mobile apps use third-party relay/appview by default (could be randomized).
> Strongly encourage backups
Or invert this, and make it local-first. It's your data, and publishing it to a network is a form of backup. Either that, or the client holds a local copy by default.