from the page
>The Facebook family of companies will still receive and use this information for other purposes such as improving infrastructure and delivery systems, understanding how our services or theirs are used, securing systems, and fighting spam, abuse, or infringement activities.
So even if you do opt out,it really does not make a difference.
[Edit] : More excerpts from the TOS(https://www.whatsapp.com/legal/#privacy-policy-information-y...)
>Account Information. Your phone number, profile name and photo, online status and status message, last seen status, and receipts may be available to anyone who uses our Services, although you can configure your Services settings to manage certain information available to other users.
> Facebook and the other companies in the Facebook family also may use information from us to improve your experiences within their services such as making product suggestions (for example, of friends or connections, or of interesting content) and showing relevant offers and ads. However, your WhatsApp messages will not be shared onto Facebook for others to see. In fact, Facebook will not use your WhatsApp messages for any purpose other than to assist us in operating and providing our Services.
The only guarantee that seems to be given is the the messages will not be shared onto Facebook( It can still be used by them)
and the [...]assist us in operating and providing our Services,I would like to see what Whatsapp describes as 'providing our Services',if they one day define 'providing contextual ads and product suggestions' as their Service we really have no option here.
Also
>New ways to use WhatsApp. We will explore ways for you and businesses to communicate with each other using WhatsApp, such as through order, transaction, and appointment information, delivery and shipping notifications, product and service updates, and marketing
This shows that once businesses onboard on Whatsapp (looking at it as wannabe WeChat),then this becomes a part of its services thereby allowing our information to flow out too.