It's life, Jim, but not as you know it
FB and Google have another, more major problem;: their business model is entirely based on the wave of government privacy abuse post 9/11 using tactics practically 100% identical to those used in the McCarthy era (only the magic word was then "communist" instead of the modern scarecrow "terrorist").
Both FB and Google are increasingly (and deservedly) under threat for their blatant ignoring of privacy which users now finally start to recognise again as their rights (it takes a while after almost 2 decades of brain washing). Their reaction so far has been to either stick their fingers in their ears and sing "I can't hear you nah nah", use service closure threats or simply change their abuse. In not a single instance has there been an iota of adjustment to their approach to business. In a way, they have already become Microsoft, other than that the monopoly status was obtained with innovation (a fact you really cannot accuse Microsoft of) these originally agile companies have now atrophied at the top.
Shareholders won't see this, of course. Most of them only see large numbers, and as long as the large numbers are massaged in the right way they will be happy with their stock. Long term, however, I would suggest planning an exit would be a good idea.
The next innovator must be around the corner - because that is the space both Google and FB have now abandoned.