There needs to be a much better solution to the use case of having to jettison from an existing federation that might be disappearing soon (or where the admin changes the rules and you no longer want to be there).
Currently, the only fix is to create a brand new account on a different federation and start again.
Again that may just be the wrong paradigm. If you are especially concerned about disappearance of a server then just run your own installation. This is partially why I'm making debian packages for GNU Social, to make that process easy.
There isn't really any "different federation". You just follow whoever you want to follow, regardless of what server they're on.
Currently, the only fix is to create a brand new account on a different federation and start again.