By the beginning of 2021, WhatsApp will be down on many phones. WhatsApp will be disabled on Apple’s iOS 9 based phones and Google’s Android 4.0.3 based phones from January 1, 2021. But WhatsApp will continue to be available on phones running iOS above iOS 9.
iPhone 4S, iPhone 5, iPhone 5S, iPhone 5C. WhatsApp will stop working on all smartphones that stopped receiving updates after the Android 4.0.3 KitKat version by January 2021. This means that WhatsApp will not be available on phones like Samsung Galaxy S2, Motorola Android Razor, LG Optimus Black, and HTC Desire.
Phones running on these OSes were not previously allowed to open a new WhatsApp account. Accounts cannot be re-verified at this time. But to make sure your phones fall into this category you can go to Settings> System> Software Update and check for system updates.