The uncles & aunties referred points to an analog generation (age > 50) in India. For a lot of them WhatsApp is the first social network experience. I am in a group in WA with extended family members and there is continuous chatter on it.

As for losing these users, they themselves are oblivious to the privacy concerns and are not that digital literate to explore other options and deploy. It will be someone young in that group who might take a lead to shift to some other messenger.