i don't know how much this has been discussed already (this centralized place is long-needed), but onboarding of new users right now is not great. if mastodon.social is closed, people hit a wall where they have to find the tiny instance list link (which they might not even notice), which for that matter requires them to already know something about how federation works. then they're left staring at a list of over a thousand instances with very little differentiation besides somewhat arbitrary techy stuff that means nothing to most people.
i'm sure you already have something in the works (joinmastodon.org itself?) for this but i thought it would be good to get this topic out in the open for more of us to weigh in on.