A platform like WhatsApp could evolve to cover the main things people are using Facebook for. History has shown that people are not too stuck on any platform.
5 seconds on google finds that adding a SnapChat stories clone is exactly where WhatsApp has gone now, just like Messenger and Instagram: https://techcrunch.com/2018/05/01/whatsapp-stories/
Personally I’ve minimized social network use and don’t think every single app needs a status broadcast feature, but it’s popular. Not just a group chat app anymore though.
Stickers are new, I must have forgotten that because every other chat app I use has had them for ages. They are really an example of WhatsApp moving slowly compared to Telegram and Discord.
Group video chats are something that's probably motivated by rising mobile speeds? As bandwidth becomes more plentiful and smartphones have plenty of RAM and CPU power there's no reason to restrict video chats to one person.