There are multiple account migration issues, the hardest is what happens when the hobbyist/volunteer instance you use inevitably goes down for good - you lose y

There are multiple account migration issues, the hardest is what happens when the hobbyist/volunteer instance you use inevitably goes down for good - you lose your address, your social network connections, your posts/history etc. That's unlikely to happen if you use the main Mastodon instance, but an aim of Mastodon is that you don't. In that situation you can't log into the old site to edit your profile to have it redirect people to a new account, and even if you could the redirect will still go down with the server. Mastodon can't fix these problems alone because the whole fediverse protocol needs to be rethought. Hubzilla saw this as the fundamental issue facing federated social media and so it was designed around a solution they call "nomadic identity" - you can shift your Hubzilla identity across many servers, keeping all your posts and subscriptions, and all the Hubzilla stuff updates and points to the new place, but subscriptions to you from Mastodon/fediverse will still break. Perhaps Mastodon can lead the work on a newer protocol for the fediverse.