I'd be surprised if they were really completely dropping it. It probably has more to do with rush to market on latest features than some attempt to slam doors on people's feet. XMPP for voice really is not all that great, I've implemented it myself.
We've supported Googleifyed xmpp jingle in FreeSWITCH [http://www.freeeswitch.org] since 2006. Its never really looked like something that would scale since the signaling protocol was over an already high level transport designed for chat. XMPP offers one really good feature, you can reach users directly using a firstname.lastname@example.org style address and there is no NAT or any other networking or lookup issues to reach that user. The downside is it won't scale due to the fact that xmpp servers are heavily rate limited and not designed at all for tons of messaging at heavy rates. So Google luckily had the best super cluster of xmpp services in town and that allowed them to build on that for the voice stuff but I bet it became clear to them quickly the challenges with trying to exponentially keep up.
I would gather more info and look for the whole story before passing judgement. If they have some goal to use some fancy new audio and video services, there is a chance they can focus on that first and make sure it scales and it should be trivial to gateway that back to xmpp for existing topology.
Coming from a telephony background, I am more concerned with the tunnel vision towards paradigm shift at any cost that threatens people who still use telephones from being disenfranchised by this attempt to reinvent communication too drastically too quickly. Balance is key when it comes to legacy vs new wave in communication technology.