One thought that comes up: Wouldn’t it be easier to have each customer in their own (logical) database? I mean, you don’t need transactions across different customers, right? So you’re essentially solving a harder problem than the one you’ve got. Not sure postgres (logical) databases would scale that well, but don’t see a principal reason why it couldn’t. Has anyone explored this further?
I imagine it only gets you so far. What do you do about customers like Walmart or Oracle? Hundreds, if not thousands, of users all leaving hundreds of comments on Figma files every day. If you want good latency without giving up strong consistency (which the article says they want) you'll need to keep sharding.
After all, Stackoverflow is running off of a handful of machines.