I hope Bluesky is able to find a model that works for them AND for consumers. (I do know it's an open protocol, so it'll live on without Bluesky itself! However, as this post shows, it's a lot of work to build on the prototype... so if not them, who? And if someone else, how will they become sustainable?)
Initially, it can be funded by selling tools that do analytics or by donations (like Wikipedia).
They've intentionally kept a low footprint to keep expenses down, and while income via donation is out of the picture (unless AT Proto grows into a full ecosystem, I suppose?), cosmetics are a tried-and-true model for supporting something that most users use for free, but that some power users spend all day on and want shiny stuff for. They'll probably end up exploring Discord-esque paywalled features for power users as well, which isn't necessarily ideal but is leagues better than getting on the currently-dying vicious cycle of Display Ads, IMO.