Whoa! itshappening.gif #mastodon
is actually learning from #hubzilla!
They're exploring nomadic identity by researching hubzilla's implementation. Support account migration · Issue #177 · tootsuite/mastodon
What you're describing is the live migration / mirroring, or "nomadic identity" system that Hubzilla uses: #177 (comment)
Under zot, any linked accounts are effectively mirrors of each other, passed back and forth between servers. Any server that is hosting your identity will share basically everything back and forth -- mentions, permissions, post history, etc. And yes, if one goes down, then everything is fine as long as any other clone is up.