The fact of the matter is that numbers speak. Facebook is my identity on the web, and I bet it is yours too. It is too late to turn back. Unless they do something 10x worse than Beacon, I'm not leaving, and I doubt you will either.
I'm afraid they control your web identity. You know what though, I'm okay with it. It makes my life easier.
I do have a Facebook profile... but I visit the site maybe once every three months, and all the data is the fake data I put in 4 years ago. My real identity is this thing called a "web page" that is the first Google result for my name.
I've a friend who is paranoid about his online identity and always gives fake data to websites. Recently he was ranting that some online car insurance thing gave him an awful quote, much worse than his present deal. Hmm, could that be because his fake identity had no credit history...?
The benefits of a coherent identity on and offline are only going to get more compelling.
No way is it too late to turn back. There is definitely a positive feedback loop involved, but I think we have an ecosystem too tuned to potential monopolies to allow this to happen without a fight.
Instead, I think we'll see social networking layer across websites generally: imagine using opensocial/oauth over multiple sites that you use, as if you could bolt Ning.com over the top of you blog or forum or startup site.
I tested out adding Google's friend connect on my wordpress personal blog. Fairly simple, but they still collect the data :( I guess a duopoly is better than a monopoly, but there's still room for web identity to develop outside of Facebook.
I'm afraid they control your web identity. You know what though, I'm okay with it. It makes my life easier.