Are you basically presenting me with an option next to xmpp/otr?
So in that case I'll stick with xmpp for my use case - self-hosting is just something that I wouldn't want to give up.
This is trying to combine 3 points on Zooko's Triangle : You want human-meaningful names (which phone numbers are, because they map to existing things), so you have to make a trade-off between decentralization and security. WhisperSystems opted for security for some reduced decentralization. For something that’s aiming to replace text messaging, I can’t really blame them for that choice.
 = https://en.wikipedia.org/wiki/Zooko%27s_triangle