Android to ditch Messaging app in favor of Hangouts for all your SMS/MMS messaging
All of this functionality will appear as Google rolls out Hangouts version 1.3 in the near future. You’d be able to share not just texts and images, but videos as well. There will be a stamp to show when a message is sent via SMS/MMS.
The update is coming up soon and is likely to not be related to any particular Android version. In terms of timing, the release of the Hangouts update could come around the KitKat update time frame.
It’s not yet certain whether Hangouts will replace Messaging on all devices, but speculation points out that it might be an experiment that will first appear in the Nexus line. Time will surely tell us soon.
source: Android Police