1. Facebook does has a great Social Network and the chances of people moving elsewhere is unlikely because they have developed a critical mass. Millions of people are already invested in Facebook. Fads are easy to change. Its not easy to opt out of Facebook because your friends drag you back. I cannot go and join another network because none of my friends are there.
2. You say the social OS is poorly executed but you have to remember its early days and I am eager to see how the integration of Parakey will change Facebook. You are right when you say there is a lot of app crap, however slowly but surely I expect better more useful apps to be developed as Facebook become more professional. Its a fun social network at the moment but I've seen my friends profiles change significantly since joining megacorp. Their profiles are now like resumes.
3. The Privacy-Invading Ad Network pisses me off. But because of number 1 (above) I think its one of those things that will be accepted as a fait-accompli. Us guys and girls in the tech community may start a fuss, but Facebook now has millions of members. We can be ignored and if the majority of people don't care, I doubt Facebook will change things.
Conclusion - Its too early to tell were Facebook is going (they probably don't even know). Somethings about it may piss us off, but the tech community's influence in Facebook will wan.