I disagree that this is even a factor to consider, and that we should be rigorous when assigning probabilities to events.
Seriously, what meaningful and controversial change has the rank-and-file (or even the managerial staff) at Facebook managed to accomplish? I'm not really asking for your opinion here as much as I am asking if you have any reports or information on the matter that contradicts the things I've heard or seen or read.
Why are you so certain? Their own employees feel that public pressure is the only way out, evidenced by their employees publicly speaking out or leaking things to the press to effect change. How, in your eyes, does this come anywhere close to a degree of certainty that change from within is possible?