I can't really see why Facebook would care; even if they drive off 50% of WhatsApp's userbase, that's 50% they get to keep, analyze, and monetize. If they made

I can't really see why Facebook would care; even if they drive off 50% of WhatsApp's userbase, that's 50% they get to keep, analyze, and monetize. If they made WhatsApp a separate entity, they lose 100% of its users. Half of something is better than all of nothing. The acquisition cost of WhatsApp is sunk at this point—the only thing left is to wring as much money out of it as possible.