[smoldesu]

That's kinda a bogus concern. As-is, Facebook can already declare that they're moving all WhatsApp clients to their New Web Version and remove all the versions off the App Store. Same goes for the rest of their apps, and it's fully possible on Android too.

But, they don't. Realistically there's no reason for them to exist anywhere besides the App/Play Store, as long as those platforms play fair. This is a real strawman argument though, considering it's fully possible in the status quo. The problem isn't Apple or the government, it's that Facebook already has a disproportionate amount of control over your life. Apple cannot save you from that with a software update.