It won't happen IMO. Our legislators are capable of thinking critically (for the most part?) and realizing what went wrong. And they know this is going to help Bitcoin evolve. It's not a flaw in Bitcoin itself. They aren't calling it the "Wild Wild West" of Bitcoin for nothing! Things will get better.
Personally I'm just more nervous that they try to stalk it to an extreme level like the internet with PRISM only applied to Bitcoin
Aka trace every address without evidence of wrongdoing just because they can then if someone is arrested use that database to implicate you as well as the defendant even if the coins plausibly were mixed before you receive them (Aka tainted coins)
Since it may be a new concept to a few gives a bit of an overview of what I mean link and explanation
http://www.bitkoins.com/discussion/5327/tainted-coins-how-colored-coins-could-be-used-against-bitcoins-anonymity/p1http://bitcoin.stackexchange.com/questions/7966/what-are-tainted-coins-exactlyIn simple terms don't mess with Fungibility