My mum has just asked me this. On one of her whatsapp chats, the persons profile pic has gone, the last seen status has gone and so have the video and call icons.
I just test-blocked DH and my profile pic and last seen status disappeared, but those icons were still there. They just didn't connect.
I assume she has been blocked but why would those icons disappear? Does it mean the person has deleted their whole WhatsApp account too?