To start with, Facebook introduced a whole plethora of new paradigms in social media. They were innovative. They created new ways of interacting with people. They revolutionized social media.
For example, we can maintain relationships in a lazy fashion by pressing the "Like" button. In that fashion we can "connect" with someone (in some sort of fashion) in less than a second.
We can have more "friends" than in real life. Indeed, Facebook (and MySpace) have challenged the definition of friend. And they have redefined how we interact with them.
But in this ever-changing world, paradigms change over night. A new paradigm is introduced, it goes viral, reaches a tipping point, creates a critical mass and suddenly it makes unwittingly billionaires out of its inventors. Everyone thinks that this is the end of the story. It's not. What was created, eventually dies.
The entire life cycle ends in death. MySpace suffered old age and near-death dropping in value to a tenth of what it sold for. Nothing is forever, and cycles are a lot quicker in a highly inter-connected world.
So, did Google create a better mousetrap with Google+ or Google Circles? I have not seen Google+ or Google Circles, but it seems that it is more closely in line with non-virtual real life social networks.
With Facebook, a friend has full privileges to my online life, unless I undertake an onerous task of specifically blocking specific people for instances of specific things. That's not how real life operates.
The knowledge that I disseminate about myself in real life depends on the audience. For example when I travel on business through my home town, several hours away, I may stop in and see one of my siblings, but I do not want them to tell my parents who live in the same city that I am there on that occasion. My mother would insist of making a meal, and keeping me there for hours when I am time constrained. I prefer leisurely planned visits so that I can take my time and enjoy catching up with my parents. So, for that particular day, I want a certain sibling to see my status but not my parents. At other times, I want my parents to know that I am coming. Connections and statuses are dynamic depending on circumstance and Facebook cannot allow for that easily.
Another example is that a young niece of mine wants me to see some prom pics, and pic of her new boyfriend, but doesn't want me to see comments about him that her friends make.
All of the content has to have the ability to be controlled irrespective of who belongs to what circle. Generic circles with generic privacy settings, of family, friends, co-workers, etc do not work all of the time.
Human nature is such that we are all somewhat egotistical and narcissistic. So even though I know that I am in the circle of co-worker with one of my fellow cubicle drones, I tend to think that I am his/her most important friend, and that person does absolutely nothing to dispel that notion.
The closer that any new social network mimics this intrinsic human behavior, the more successful that it will be, and it will supplant the older paradigms.
So die Facebook die. You have been good to us, but unless you fundamentally change, you are on the way to the boneyard. Is Google+ the new way to go? Maybe, however as a humanist I would like to believe that a bunch of engineers cannot come up with the next best thing since sliced Facebook. It would have to be some unkempt guys spooging code for the fun of it, and not some dark force of dominance who's motto is "Do No Evil".