You can't cut of bitcoin transactions because there is by its very definition no place to cut them of.
If this is the case, we are only going to get that much closer to the end game.
While many people (myself included) would love to see a cryptographic currency replace all existing currencies, it needs a transition period to have a good chance of succeeding, and making it illegal would eliminate that transition period.
It would be great if there was a tool to literally facilitate this transaction without directly giving from one company to another, thus bypassing SOPA. I give the "holder" $10, the "holder" gives me 10 BTC. Then I give 10 BTC to say PirateBay. Then the "holder" guarantees that piratebay can sell 10 BTC to them for $10. Thats it. They only converted BTC to/from cash. I directly gave BTC to pirate bay. SOPA is ignored.
HOWEVER THIS IS EXACTLY WHAT THE INTERNET IS AGAINST. This will prevent all sort of anti-fraud that is going on now. You will wind up bypassing years of innovation to create a black market. It will be detremental.
Right now, in meatspace, I have both options: I can pay with cash and have little to no recourse or record, or I can pay with check or credit card and have a record and various fraud protection measures. I want to have both options on the Internet as well.
Also note that various bitcoin escrow agencies have popped up, which serve the obvious function. Assuming an agency exists that both parties trust, you can have the fraud protection you want if and when you want it.
But bitcoin escrow agencies don't solve the SOPA problem -- once you have a small number of intermediaries paying these websites, they become the place where the law can apply its force. They will be ordered/coerced to stop funding ThePirateBay or whatever site the media industry targets, so these sites either can't have reliable BC payments or they are subject to being cut off by these laws without trial.
What's the solution today?
If you cut any site off from Google/DoubleClick, you've effectively prevented them from monetizing through advertising enough to reach top 100.
That's not every site's business model, but there's certainly a class of sites we'd like to exist (of which YouTube is a prime example) that would not be able to exist without access to the US advertising networks.
We can route around DNS blocks to get to the sites, but what does that matter if the sites close themselves because their funding was cut off? A site like YouTube would not be profitable without access to US-based ad networks.