WhatsApp will stop supporting BlackBerry 10 and Windows Phone 8.0 from December 31st 2017. WhatsApp had announced earlier that it will continue to support Android 2.3 till 2020. The company had already stopped support for Android versions older than 2.3.3 and Windows Phone 7 back in 2016.
The Facebook owned messaging app has already announced its decision to stop development for these platforms so some of the features may stop functioning at any time. Along with BlackBerry OS and Windows Phone 8.0, the company is also ending support for Nokia S40 post December 31, 2018.