Ubiquity is an interesting thought - there are very few apps that an average person uses on a daily basis that _aren't_ owned by Facebook. Four of the most used apps (Facebook, Messenger, Instagram, WhatsApp) are owned by the same parent company.
In China, we see an analogous example - to an even greater extent - WeChat is practically the de facto mobile OS. Where do we go from here? Hardware? WeChat seems most likely to do this, from my perspective. What happens when Tencent acquires Xiaomi and creates WeChatOS phones? What happens when Facebook does similar and Mark Zuckerberg controls nearly every waking moment of most Americans? Who is the Apple to the United States v. Facebook monopoly?