The problem with XMPP seems to be that it is stuck in extension hell. There is simply too many XEPs bouncing around.
The last great hope was back when both Facebook and Google used it, and you could connect one to the other.
Since then both have gone proprietary, and dragged their user base with them.
But I hope for the return of XMPP. While the client development stagnated for the most part over the last years, there are a few which seem to catch up with the innovation of the last years (conversations, chat secure).