WhatsApp will gradually stop working if you don't agree to the new privacy policy.
It will effectively become useless for any users that refuse the new privacy policy. WhatsApp said that they will eventually stop users from sending and receiving messages and after several weeks users will begin to lose access to their chat lists. And a few weeks after that, users won't receive calls or notifications. Link
Update: WhatsApp backtracks and says they now won’t limit functionality if you don’t accept their new privacy policy - Update link
