In a blog post, Google says the change is specific to subscribers of its G Suite productivity platform. Those users will be transitioned from classic Hangouts to Hangouts Chat and Hangouts Meet. The first step in the transition will begin on April 16, 2019 with the following changes:

April 16, 2019 – Several changes that may require administrator action (see below for details). Between April and September 2019 – Features from classic Hangouts will come to Chat. October 2019 – Start retiring classic Hangouts for G Suite customers.

Google says consumer-end users of the classic Hangouts will see no change as Google will continue to support the app. However, the company did say it plans a consumer transition eventually, stating it will occur after the G Suite migration is complete.

Upcoming Changes

From April 16, Chat will become available on the web through mobile devices, while the classic experience will remain on Gmail, mobile, and the Chrome extension. As for admins, they will see the following changes:

For Google Vault customers, Mail retention rules and holds will stop protecting chat messages in classic Hangouts. Instead, Chat retention rules and holds will protect chat messages in both classic Hangouts and Chat. Chat admin settings will now control chat capability in both classic Hangouts and Chat. A new setting in the Admin console under Apps > G Suite > Hangouts Chat will be added so you can disable classic Hangouts user interfaces at a time of your choosing. The “Google Hangouts” settings page in the Admin console will be renamed “Hangouts Meet.” This setting will control both classic Hangouts video and Hangouts Meet. Google Shuttering Classic Hangouts for G Suite Customers in April - 7Google Shuttering Classic Hangouts for G Suite Customers in April - 26Google Shuttering Classic Hangouts for G Suite Customers in April - 9Google Shuttering Classic Hangouts for G Suite Customers in April - 76Google Shuttering Classic Hangouts for G Suite Customers in April - 48