Google+ is the rapidly growing seed of a web-wide social backbone, and the catalyst for the ultimate uniting of the social graph. All it will take on Google’s part is a step of openness to bring about such a commoditization of the social layer. This would not only be egalitarian, but would also be the most effective competitive measure against Facebook.
As web search connects people to documents across the web, the social backbone connects people to each other directly, across the full span of web-wide activity. (For the avoidance of doubt, I take “web” to include networked phone and tablet applications, even if the web use is invisible to the user.)
Search removed the need to remember domain names and URLs. It’s a superior way to locate content. The social backbone will relieve our need to manage email addresses and save us laborious “friending” and permission-granting activity — in addition to providing other common services such as notification and sharing.
Connecting search with social would be a huge step to completing the social graph. Currently Facebook has the lead on this one, but if Google is able to sidestep the privacy issues, which have been thorny, they could capture the pie.