Earlier quoted context omitted.
Just wondering, but why not just use XMPP? You can choose any server that you like or trust, or run your own (on your own or third party infrastructure, up to you), and use OTR for end-to-end encryption if you feel you need to¹. I have been using XMPP since 2000/2001. My current address is nine years old (and I control the server). I have a choice of clients on every platform that I use. All my contacts have the same…
Is OTR really a practical option? You message seems unclear about it. Also, how do you get all your contacts to use XMPP and your server?
Convince them :-) Same as with any other.