@Euphoria I'd be careful with this. When I talked about the 500 characters limit on Mastodon, I talked about Mastodon, that's what I meant. I wasn't talking about the underlying protocol or the extended federation of non-Mastodon OStatus-implementing instances.
Federation is also nice in the sense that instances can cluster themselves around (m)any axis. If a majority of instance admins decide not to federate with instances not respecting 500char, well…