I still use XMPP to connect to google talk and converse with people who are using hangouts. I use "Conversations" on Android, which works well and also supports OMEMO (the XMPP version of the encryption behind Signal/Whatsapp/etc). I'm effectively doing the equivalent of your facebook+xmpp+otr setup today, but it's googlechat+xmpp+omemo.

The author of Conversations recently wrote up the state of XMPP in 2016: https://gultsch.de/xmpp_2016.html

So, though you may not be using it anymore, XMPP is far from a dead end.