Earlier in the year, WhatsApp announced that they were ending support for several mobile platforms by the end of this year as a result of the low numbers they now have and also their inability to suport new features in the more modern versions of the app.
However, it now seems that they have decided to extend the deadline by six months. This means that unlike the initial deadline which was 31st of December, 2016, support for these devices will now end by June 30th, 2017.
This was made known via an update to the FAQ section on their website and an update to the apps on those platforms. To take advantage of the extension, you will have to update your current version.