You’ve highlighted what is definitely a major problem with the Fediverse - all it takes for you to lose all the hard work you’ve done building up a community is the person running a server to pull the plug with no warning.
I loved kbin social - I started out on there, and only moved over to lemmy because it was getting too erratic and it was impossible to find out what was going on. Being able to move is a great thing, but if you miss your window to move, you’re SOL.
Admins definitely need to be willing and able to have the reins over to someone else if it’s getting to be too much, or to at least let people know in advance if they’re planning to shut down. Communication is key.