FYI: WhatsApp ending support for BlackBerry OS and BlackBerry 10 on December 31
Although in the first announcement WhatsApp said the application will stop working on mobile platforms that are no longer supported, a more recent update suggests users will not be able to create new accounts, nor re-verify existing accounts. The good news is you'll be able to continue to use WhatsApp even after December 31.
Keep in mind though that since WhatsApp will no longer actively develop for BlackBerry OS and BlackBerry 10, some features may stop working at any time.
In the same piece of news, WhatsApp confirmed it will end support for Windows Phone 8.0 on the same day, December 31, 2017. Moreover, two other platforms, Nokia S40 and Android 2.3.7 and older will no longer be supported starting December 31, 2018 and February 1, 2020, respectively.