An interview with one of WhatsApp's co-founders earlier this week confirmed that Brian Acton and Jan Koum (also co-founders of WhatsApp) have left Facebook after having significant differences with Mark Zuckerberg over how WhatsApp wants to make money. The same interview mentions that the app will soon include ads, and explains what will happen to the end-to-end encryption that already exists.

We always knew Facebook would want to destroy the app one day, and it seems that moment is approaching. In a way, it's understandable, as it wants to make a profit on the $22 billion it paid to buy it. The original goal was to reach $10 billion in revenue within the first 5 years.
The ads will start appearing in early 2019. However, Facebook has already tried several times to introduce (indirectly or directly) ads into the application. Initially, it tried to "connect" common users between Facebook and WhatsApp, and display ads from the Facebook platform, which not only failed, but also forced the company to pay a fine of 122 million, and the removal of this particular feature.
Facebook wants to introduce targeted ads to users' statuses, something that will happen next year. But what will happen to WhatsApp's end-to-end encryption? Nothing at the moment. It should be noted that since the service provides encrypted messaging, Facebook and WhatsApp cannot see users' messages.
