For Google Talk users, Product Manager Mayur Kamat has some good news and some bad news. The bad news is that the chat service's desktop client for Windows will be deprecated on February 23, 2015 as the team continues to focus on making Hangouts better.
Of course that leaves the question of third-party clients like Pidgin, Trillian, etc. The good news is, as Kamat notes, that compatible apps will still continue to work.
If you’re not ready to make the switch to Hangouts quite yet, you can continue using Google Talk on Windows with a range of compatible third-party chat apps (http://goo.gl/FSbCX5). Please keep in mind these aren’t Google products, so exercise caution when signing in with your Google account.
If you do want to make the jump to Hangouts, Kamat of course notes that Gmail on desktop or the Hangouts Chrome app will have you up and running.
It's clear that Google wants to push adoption of Hangouts and let Talk fade to black, but it's at least nice to see that loyal Talk users won't be completely left out in the cold.