It's sourced. That's a reply to a thread based here, which starts by quoting email from Google which says point blank that "the new [hangouts] service will not support XMPP".
> Your users may use any chat client that supports XMPP. XMPP clients will continue to work as usual with the App Engine XMPP service.
> Note that the changes discussed above have no impact on non-Google XMPP clients
Why this utter confusion over a simple thing after a whole three hour keynote yesterday and today no one seems to have a clue? Communication fail, if you ask me.
Color me skeptical, but there was similar confusion when SMS search stopped working suddenly,and then people realized Google killed it. XMPP support may stay, but I am not going to bet more than 2 bucks on it.