I don't think SOPA will fly, ultimately. It benefits content companies at the expense of technology companies which by now seem to have deeper pockets. Technology companies will find a way to undo SOPA if it passes.
But suppose it passes and is consistently enforced. This threatens sites "enabling or facilitating copyright infringement" - what are those?
Standalone personal sites probably aren't threatened. You know what you publish, and if you publish copyrighted content, you can easily remove it. Gmail probably isn't threatened because data isn't publicly available. SOPA does threaten Wikipedia, because you're supposed to not link to "infringing sites" (which could be anything) - but it probably doesn't threaten them through the content actually on the site, since they're very careful not to use copyrighted content.
Which sites are threatened the most? Facebook, YouTube, blogging and social networking sites. Plenty of copyrighted content gets uploaded to these. If SOPA is trimmed to exclude links to "infringing sites", then it is mostly "social" sites which are targeted.
Are these sites a good development in the Internet world? It's definitely not how the Internet was supposed to look like. Instead of many individual sites, we now have a few huge sites keeping most of the published data, together with much personal information, with very little obligations to users. "They trust me - dumb fucks", as the Facebook CEO put it.
Wouldn't it be great if instead of big social sites, we had big hosting companies and many independent individual sites? Wouldn't it be great if the many independent sites were all using public protocols to exchange data - using the Internet network and not the Facebook network? Wouldn't it be great if no "social engineer" could oversee our communication?
Couldn't SOPA do just that - make it unaffordable to manage a proprietary network like Facebook on top of the Internet, giving us back a decentralized Internet? Facebook convinced hundreds of millions of users that it's fun to be on the Internet, read stuff, write stuff. Couldn't SOPA then force people out of Facebook and bring them to the actual Internet?
Hosting companies that make publishing easy - on your site, under your domain, with data under your full control and responsibility - could use the opportunity. It's well past time that running an actual site is feasible on this fabulous Internet network. With all these proprietary networks on top, what normal person runs a site today, or even knows what it means? Wouldn't it be great if they finally started?
And yeah, I realize it's not going to be like that. Facebook will manage to shoot this legislation down. If it doesn't, then it'll manage to work around its enforcement. And if it doesn't, any site with a link to any other site is probably threatened - definitely Wikipedia, Reddit, HN…
So yeah, it's going to be much worse. But I can dream, can't I?
(And couldn't you think of a way to distribute the hosting of user-generated contents - like news links or Wikipedia articles - and give a unified view at the client side? Then one couldn't target "the Wikipedia site" - there wouldn't be any - but only a specific portion. Wouldn't it be better for users, in some ways? )