From where exactly did you hear this? Almost all the WhatsApp users that I know of in person have already accepted the new privacy policy. While 8 out of 10 knew there is a potential privacy risk and that there are other better alternative services, only 3 out of the 10 even decided to try other services and they eventually returned back to Watsapp. Even the high ranking officials like the District Collectors and Secretaries of Government are sharing official letters over WhatsApp nowadays
Unless they somehow manage to get a good user base, I don't think that they'll replace Watsapp in the near future. And the use of blockchain tech is just going with the current trend.