I don't know if we can draw much from the comparison to WeChat. WeChat is effectively an operating system for the domestic Chinese economy within a single app,

I don't know if we can draw much from the comparison to WeChat. WeChat is effectively an operating system for the domestic Chinese economy within a single app, it's 10-100x more complex than a messaging app, and it enjoys official blessing that WhatsApp would never obtain in any market. You can hardly survive in China without WeChat, it's so tightly integrated into everyday life.