How will voice be integrated into hangouts?

It's pretty clear it's coming (do we know exactly when?) but has google given any indication of what they're going to do with all the existing GV users? I wonder especially what'll happen to those of us who use our google voice number for everything, but still have a regular number attached to our phone. Will we have to port the gv number to keep it?

I'm asking partly out of curiosity and partly because I'm at the breaking point with voice. I'm ready to leave (I've missed one too many group texts), but if a switch is coming soon it might be worth sticking it out rather than going through the porting process.