To believe this would have more than a cursory effect on free speech you would have to believe several things.
First, you'd have to believe they actually want to monitor the entire WWW and become the thought police
Second, you'd have to believe they have the resources to do it. Right Now, I don't even think it's possible, trillions of transactions in conversation daily, many encrypted at various levels.
Third, you'd have to believe they controlled access to the network itself on a wholesale level, do they? I don't know, I'm genuinely asking,but I'm guessing, given the challenges with getting addresses even when blatant crimes are committed, that they cannot bring enough resources to bare, on shutting it down for any but the most agregious offenders.