No one will have their accounts deleted or lose functionality of WhatsApp on May 15th because of this update.
Considering the majority of users who have seen the update have accepted, we'll continue to display a notification in WhatsApp providing more information about the update and reminding those who haven’t had a chance to do so to review and accept. We currently have no plans for these reminders to become persistent and to limit the functionality of the app.
There will also be other opportunities for those who haven’t accepted the updates to do so directly in the app. For example, when someone reregisters for WhatsApp or if someone wants to use a feature that's related to this update for the first time.
WhatsApp won’t delete your account if you don’t accept the update.