BlackBerry senior marketing manager, developer relations Lou Gazzola shared the news in a blog post:

The app landscape continues to evolve, and in ways that are not always within our control. Recently, Facebook made the decision to discontinue support of its essential APIs (application-programming interfaces) for BlackBerry, and WhatsApp announced that it would end support for BlackBerry 10 and BBOS at the end of 2016.

We are extremely disappointed in their decision, as we know so many users love these apps. We fought back to work with WhatsApp and Facebook to change their minds, but at this time, their decision stands (but let them know how you feel on social media, using the hashtag #ILoveBB10Apps). Despite this, we have worked hard to ensure that our end-users have the best experience in light of this decision, and we are continuing to search for alternate solutions.