“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”, said WhatsApp in its FAQ page.
What will happen to users after this restricted use period? It is not clear. But the WhatsApp FAQ page states that, as of May 15, the “inactive users” rule will apply, which consists of deleting accounts after 120 days of inactivity.