If the law passes, Wikipedia will die. It's as simple as that. Anyone who thinks otherwise is deluding themselves.
• it's unlikely that it would be used against Wikipedia for fear of backlash – smaller sites have much more to fear
• the law could be struck down by the courts on 1st amendment grounds, or modified/repealed before any application to Wikipedia
• Wikipedia could move to another jurisdiction
• etc., etc., etc.
SOPA is bad, and should be voted down, and failing that should be struck down by the courts. There's lots of equally bad legislation in the USA and elsewhere, every year. The principle of neutrality lets Wikipedia keep doing its main job, year-in and year-out, without constant 'interrupts' generated by the ephemera of silly politics.
Small comfort to any of the American contributors and users.
The threat of use is often significantly worse than the use itself. Realistically, big sites like, say, Google are not going to get shut down for a violation of a silly Internet law; the backlash is too big. That doesn't stop Google from being one of the most zealous enforcers of legislation like COPPA or DMCA, because the cost of a lawsuit, when you have gigantic pockets that can be raided, is simply too large a risk for them to take.
Same with SOPA. No big company will ever be sued under SOPA. They simply won't provide platforms for user-generated content, and then the Internet as we know it ceases to exist.
(Same with startups: would you start a company to fill that void if you knew that the first thing that'd happen if you became popular was that you'd be sued for a potentially dream-ending sum of money?)
http://en.wikipedia.org/wiki/SOPA#Bill_targets_more_than_inf...
Wikipedia links to The Pirate Bay. Furthermore, it would be absurd for Wikipedia not to link to The Pirate Bay.
Examples abound: which "leakers" are prosecuted? The ones "leaking" secret government data which the government wants you to know (i.e. how Iran is supposedly in dealings with Somalia), or the ones leaking government data which it doesn't want you to know (i.e. Bradley Manning)?
When the law is so broad that everyone's a criminal, and enforcement is capricious and politically motivated, we are at a low point in the tradition of a just society governed by the rule of law.
Or more accurately, Wikipedia wouldn't take it to court: they'd censor themselves instead, so that they could stay on the internet. Which makes SOPA an existential threat to Wikipedia as a source of knowledge.