The image you're seeing below popped up on Reddit this morning, and likely various tip boxes of numerous websites, offering a glimpse of what appears to be impending Google Voice and Hangouts integration - the holy grail we've all been seeking since the very announcement of Hangouts as a thing.
Exciting, right? Well, curb your enthusiasm, because there's really not much to see here, in all likelihood. We've seen this migration message inside the Hangouts APK since April, and the graphic assets for this prompt have probably been in there for a while, too. How did this person get the message to appear, though? Well, it turns out that he's using a root app to access the Hangouts debug mode, so there's basically zero reason to believe this prompt is at all new. It could be, it just isn't terribly likely. It also doesn't do anything right now - it's just a couple of functionless buttons. The same goes for this video.
Hangouts and Voice integration may only be closer in the sense that it's closer than it was 2 months ago, but that's still a wholly unknown amount of time.