According to those who have already had access to the update, the messenger makes it very clear that it is mandatory to accept the new terms under penalty of having the account blocked on May 15th.
WhatsApp also explains in detail that only conversations with companies will have their data and information shared with Facebook. The other private chats must remain confidential, since there is end-to-end encryption.
For now, the new banner is being distributed in some countries, but soon it will also be available to the vast majority of users. WhatsApp’s intention is to get everyone to accept the new terms by the month of May.
Therefore, WhatsApp should work to further enhance backup security and even mess with self-destructive messages. The intention is to reinforce that the platform is safe.