In my environment (Netherlands) I'd say that WhatsApp is now the primary social networking tool for most people. I wonder how that is going to work out for Facebook.

Facebook owns WhatsApp. The question is what they are going to do with it. WhatsApp with end to end encryption seems to not allow for the type of monetization people are talking about here.

That's what I mean: how will they monetize it? They'll probably introduce business / bot accounts that they can monetize, but the encryption makes all sorts of monetization schemes hard - which is what I like about it.

Maybe it's possible to do ad-targeting on the client.

Facebook bought Whatsapp two years ago.

What's done is done. Facebook won't delete your data, once U registered, give your gender/age, you are probably forever screwed, forever becoming a data point that waiting to be targeted.