Google has been slowly integrating many of its communication services into Google Hangouts, before the Voice functionality overlaps and SMS integration, we saw both Messenger and Talk roll over as well. Like the report mentions, it is likely we will be seeing more of this type of consolidation from Google down the line as more and more of these types of services get rolled into a single application. Apple has also been bringing more of its communications services and features into a more unified location with respect to FaceTime and iMessages.
Another interesting feature said to be a possibility here is that we could see the phone calling via VoIP functionality available on Gmail through the web slide over into Hangouts, according to the report. This could potentially allow users to have a fully enabled smartphone with just a data plan, likely something carriers will not take kindly to.
At this point there is no official word on this, but we could see an announcement in the coming months just in time for Google I/O.