Facebook The Platform's userbase keeps getting older and less engaged, millennials and younger have largely shifted to instagram. Taken by itself, Facebook the platform doesn't have great looking prospects.
Instagram is the current hot thing, and is keeping Facebook The Company on the growth trajectory, but it too will suffer the same problem eventually.
Now that Zuck is under so much scrutiny, he won't be allowed to acquire the next hot social platform. When instagram isn't the "it" platform anymore, Facebook is doomed.
My prediction: if the US government does nothing, Facebook the company will slowly peak and then start shrinking over the next 5-10 years and the problem will start solving itself.
Their data moat becomes infinitely less valuable if the graph of users and engagement is a downward slope instead of an upward one.