To be clear, I don't know if you'll actually be able to restore an account from an indexing server. The protocol doc assumes you'll do it from your CLIENT. Which means that the app you post from is expected to make a persistent backup of your entire account—"contingent on the disk space available." So if the idea of being able to port your entire post history around is a big selling point for Bluesky, expect to eventually have dozens of gigs of account data riding around on your phone.
Let's assume space isn't an issue. You connect to Bluesky from your desktop computer, and its got storage enough to handle decades worth of image-and video-heavy account backups. Your account is safe, right? Maybe. To recover an account hosted by a failed PDS you'll need your recovery key, so make sure you don't lose that. And there's a 72-hour window in which it can override the signing key, so make sure none of this happens while you're taking a week-long break from social media.