@pwm I am implementing a similar system to the Streams server with nomadic identity. In addition to your main server, every time you post, it is replicated to one or more other servers. At any time you can direct people to one of the replicas and start posting your main there and all your posts are retained. if main server dies before you can migrate then people just follow your new one.

This isn't directly compatible with Pleroma and inferior alternatives. I will be constructing a facade server for compatibility with regular Fedi servers, but between other decentralized ones like Streams it should just work.