The FAQ page states that WhatsApp will not delete the accounts of users who do not accept the new terms, but that they won’t be able to use it like they normally do.
“If you haven’t accepted by then, WhatsApp will not delete your account. However, you won’t have full functionality of WhatsApp until you accept. For a short time, you’ll be able to receive calls and notifications, but won’t be able to read or send messages from the app,” WhatsApp wrote.
“To maintain security, limit data retention, and protect the privacy of our users, WhatsApp accounts are generally deleted after 120 days of inactivity,” WhatsApp states. “Content stored locally on a user’s device prior to account deletion will remain until WhatsApp is deleted from the device. When a user reregisters for WhatsApp on the same device, their locally stored content will reappear.”