Despite launching Google Hangouts back in 2013, the search giant has still allowed Google Talk users to continue using the service, even though the app hasn't been available for quite a few years, and hasn't received any updates since Hangouts launched. However that is about to change. Reportedly, Google Talk will finally be retired on June 26th. As of that date, the service will stop working entirely. Which means those final few holdouts will have to make the move over to Hangouts or Allo, or another messaging service that is not run by Google.
Google Talk users will be encouraged to jump to Hangouts in the coming weeks. With Google sending them "invites" to join Hangouts - even though the service doesn't require an invite - to help move them along. It may seem a bit strange for Google to be pushing Google Talk users to Hangouts and not Allo. And well that is because Allo does not yet have a desktop client, while Hangouts does. And it's a pretty well-known fact that the majority of the Google Talk users are still using the service on the desktop. Allowing them to talk with others through their desktop as well a their smartphone instead of one or the other.
Right now, Hangouts is going through a bit of a transition, with it being moved closer to an Enterprise service for Enterprise users, and then Allo along with Duo being aimed at consumers. But Allo doesn't have a desktop client just yet, so Google can't exactly push all of their Hangouts users over to Allo just yet. Google recently launched Hangouts Chat and Hangouts Meet, with Hangouts Chat being a chat service and Hangouts Meet being a video service similar to Skype, allowing users to chat with other people over video, and it's particularly built for web meetings. To compete with Skype but also enterprise solutions like Cisco's WebEx.
Those of you who are still using Google Talk, you have just a couple of short months to make the switch over to Google Hangouts before Talk is officially retired. All of your contacts and your conversations should sync with Hangouts, and it's actually pretty easy to switch, so there shouldn't be any problems there.