> XMPP was invented at a time, where communicating online meant sending a message from one device to another. However, the modern expectations for messaging apps are much more than that. Sending media, using multiple devices, deleting messages, editing messages, read receipts, notifications when typing, group chats, threads, and even managing communities are all things a modern messenger app should be able to do.
XMPP provides all of these features and manages to keep up with commercial products really well. Everything Slack or Discord offer is there in the XMPP protocol. And if it wasn't, it could be relatively easily added, thanks to it being extensible.
However, navigating the protocol and software supporting it requires a little bit of know-how. If the OP is interested in building a product incorporating instant messaging and the satellite features, I'd suggest partnering up with somebody with this know-how. Scalable servers would be MongooseIM or ejabberd, polished clients are Conversations or Movim.
If it's a question about which protocol to use for a homeserver, then maybe something focused on ease of setup would work best, like Prosody.
> The fundamental operating principle has shifted from mere message passing to synchronising a common state between all participants.
So it should all be based on blockchain, shouldn't it? ;)