The federation/migration problem in mastodon seems very important. My broader thought: SMTP/NNTP/etc. thrived because of a set of trusted entities (govt/uni) that could reliably run federated servers. My choice of server is going to be based on which one is most likely to be up and running years in the future.

Who should those entities be today?

I bet someone has already proposed using blockchain to enforce global username uniqueness, so that accountnames aren't tied to an instance. Am I right?
@auerbach oh...it's come up a time or two :P
@argumatronic If someone suggests Urbit, I'm outta here.