Could new data sharing policy drive users to competing services?
One would be an exodus of users to the competition. There are many alternatives, though none are nearly as popular in North America; the only one that even comes close to competing in terms of active users is Facebook Messenger. This could create an opening for a competitor, however, something that Elon Musk has seemed to sense with his recent promotion of encrypted messaging app Signal. Musk specifically called out Facebook for privacy issues, and his tweet was soon retweeted by Twitter CEO Jack Dorsey leading to a massive surge of users checking out the previously somewhat obscure platform. Signal is privately owned by the Signal Foundation; its encryption is used by WhatsApp and Facebook Messenger as well as Skype.
Another would be further fuel for antitrust investigations. The Federal Trade Commission (FTC) is weighing a possible case and is expected to announce a decision soon, and the Department of Justice has an ongoing antitrust probe that has been joined by nearly all of the state attorneys general.
Facebook has indicated that WhatsApp messages will remain encrypted end-to-end, so the company should not be scanning their contents. However, it is seeking to integrate WhatsApp with many of its other services and appears to want to use all registered and observable personal information and transaction data with those services as well. Though WhatsApp does not presently scan messages for advertising or data sharing purposes, it is widely believed that it draws on Facebook account information to aid in selecting personalized ads for WhatsApp users. It can also draw 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 that the app is used and message recipient identities (and their attached Facebook information) among other data points that determine what ads the user ends up seeing.