Google has made it pretty clear that they are going to be making changes to Voice and merging it with Hangouts even more than it is now.
I have an Obi integrated with Google Voice and it is still working great with both incoming and outgoing calls.
But, I think the next thing to watch is Google I/O. Lets see what they announce there. It might be whatever they are doing with their support/lack of support for XMPP they are going to wait until they release a newer version of Hangouts that fully encapsulates Google Voice. Or, they could have changed their mind (which would be appropriate because last year Larry Page got up on stage and chewed out Oracle and Microsoft for not supporting standards right as Google said they were dropping support for XMPP).
Anyway, the saga continues and I love my Obi.