https://techcrunch.com/2018/05/29/google-starts-migrating-all-g-suite-users-from-hangouts-to-meet/

Google today announced that starting now, it is moving all of its G Suite users who follow its recommended schedule from its Hangouts video chat service to Hangouts Meet, the more enterprise-ready version of Hangouts. The move will likely take about a month or so.

This means all newly created Calendar invites will now link to Meet video meetings, though Google stresses that all previously created meetings won’t be affected by this.