Firstly, after a number of week the app will prompt users with pop-up to make them accept the new terms, and users will not be able to access their messages as they usually do. They will only be able to accept incoming calls and message users from whom they receive a message, by tapping on notifications of such messages. And then, there’s the kicker: “After a few weeks of limited functionality, you won’t be able to receive incoming calls or notifications and WhatsApp will stop sending messages and calls to your phone.” WhatsApp services will essentially stop for these users.
These timelines are not defined clearly — WhatsApp isn’t specifying after how many weeks the reminders will become persistent, and subsequently how long it will take for notifications to stop. But when that last consequence kicks in, users will have four months (120 days) before their WhatsApp account is deleted under the service’s inactive user policy.