this is called forking the feed, and it results in conflicting views propogating irreconcilliably throughout the network and segmenting the network's view of the feed.

the network would remain\ split. currently there is no mechanism for a node to change which fork of a feed it replicates, other than by resyncing its whole log

@elavoie TODO: implement fork proofs. if you see two seemly valid messages with the same sequence, you could publish a "fork proof" that shows that feed has forked, and other peers seeing that and validating the proof would then stop replicating that feed. This feature was mainly waiting on ssb-ooo.

This will mean that if you copy someone's keys the worse you could do would be kill their identity (they'd have to start again, same as if they lost their key)... although if you never published anything you could still read their private messages.

yes, it is a very bad thing, but stealing your identity and impersonating you would be worse!

Likes/votes already serve that indirect purpose also

since this reply I am currently writing will point to the hash of your message, it means that my signature also signs your message - by signing my message which contains your hash. If you feed is compromised and they try to fork your feed at an early point, well if you believed my feed was still secure, you could see that I has interacted with this fork of it at this point... so you could calculate a "socially longest chain"... you could get other "consensus" style properties out of this too, I just havn't thought about it too deeply because there is so much else to work on. (note: none of this would work if messages replied to your feed+seq number, because that would still be valid on the fork)