In addition to officially calling for the end to SMS on Hangouts, the G Suites blog is alerting administrators to some major streamlining in Google’s chat mediums that you should know about, too.
First of all, it’s now painfully clear that Android Messages (formerly Google Messenger) is to be king of SMS and RCS messaging from now on, thus, the need to chop Hangouts integration of SMS into bits on May 22. Google Voice and Project Fi users will not be impacted by this change.
The old Google Talk XMPP client, which technically gave users outside access to Hangouts conversations once some merging happened in 2013, is officially dying as well. Gmail users will see it gone after June 26, replaced by Hangouts. The Google Talk Android app, long deprecated, will simply stop work then. Third-party XMPP clients will adjust to work with Hangouts.
The feature playground that was Gmail Labs will be no more as Gmail Add-Ons is set to replace them as more utilitarian plug-and-play solutions. Gmail will also lose Google+ circles and the ability to email Google+ profiles as well. These changes occur no earlier than April 24.