Just in case you had forgotten, WhatsApp will be dropping support for devices running on BlackBerry OS, BlackBerry 10 and Windows Phone 8.0 and older devices on December 31, 2017. Starting next year, you will not be able to use WhatsApp on these platforms.
Earlier this year, WhatsApp confirmed its plans to sunset the BlackBerry and Windows Phone versions of the service. The company also announced deadlines for other platforms. Nokia's Series 40 devices, for example, will be supported till December 31, 2018 while Android 2.3.7 and older devices will be supported till February 1, 2020.
WhatsApp is quite remarkable in its support for older platforms and devices. However, there is a limit to everything and we can't blame them for dropping support for these platforms, even though it is coming long after their makers dropped support for them.
On the upside, this might be the reason for some users to finally upgrade to newer devices.