Facebook needed to be disrupted, but unfortunately the main way Facebook needed (and needs) to be disrupted is in compartmentalising sharing better, and while Circles accomplishes some of that, Googles real name policy pisses all over it.
As a user of Facebook and Linkedin I'm only moderately happy with the experience but I can't see myself changing soon. I would be happy to change to one social network that could "compartmentalize sharing better" (using your words) and be used for both social and work issues. If they could add some twitter functionality would be a plus. Is not efficient using different platforms all the time, would be easier to have one platform with different "modes".
There is plenty of space to disrupt the market but the status quo here is very strong. The problem is not if somebody changes or not, the problem is that everybody needs to change in mass or the network will be useless.
