Could the new data sharing policy lead users to competing services?
One would be an exodus of users to the competition. There are many alternatives, although none are as popular in North America; the only one that even comes close to competing in terms of active users is Facebook Messenger. However, this could create an opportunity for a competitor, something Elon Musk seems to feel with his recent promotion of the encrypted messaging app Signal. Musk specifically called out Facebook for privacy concerns, and his tweet was soon retweeted by Twitter CEO Jack Dorsey, prompting a massive surge of users who checked the previously somewhat obscure platform. Signal is the private property of the Signal Foundation; its encryption is used by WhatsApp and Facebook Messenger, as well as Skype.
Another would be more fuel for antitrust investigations. The Federal Trade Commission (FTC) is weighing a possible case and is expected to announce a decision soon, and the Justice Department has an antitrust investigation underway that nearly every state attorney general has joined.
Facebook has indicated that WhatsApp messages will remain encrypted end-to-end, so the company should not be scanning their content. However, you are looking to integrate WhatsApp with many of your other services and seem to want to use all your recorded and observable personal information and transaction data with those services as well. Although WhatsApp does not currently scan messages for advertising or data sharing purposes, it is believed that it relies on Facebook account information to help select personalized ads for WhatsApp users. It can also be based on a variety of other information that does not involve the actual messages sent and received: user location data, how much time they spend on the platform, the time of day the application is used, and the identities of the message recipients. (and its attached Facebook information) among other data points that determine which ads the user ends up seeing.