I mean, yeah, any instance could be gone at any time. Anything can disappear at any time. Don’t overthink it. Just pick a new instance at random like you did before. Export and import settings. Leave a note on your profile where your new account is. Once lemm.ee is gone, your account’s info page will forever say where your new account is. This instance shutting down doesn’t mean your old comments and posts disappear. Sure, you won’t be able to directly respond to them, but they aren’t vanishing.

It sucks, and it’s an annoyance, but it’s hardly the end of the world.

Think about if this were a non-federated platform. You’d be shit out of luck. All your posts and comments would be gone forever. All of everyone’s content from your instance would just be lost to time when the server shits down. But with federation it gets copied to other instances. It will live on there. The only time it won’t be is if someone makes a new instance after lemm.ee is gone, they won’t be able to pull in old lemm.ee stuff.