I know you are deeply interested in social apps, and have invaluable insight into their workings from early days at Facebook and personal in-depth research. I'm pretty sure you were username n on an app I built too...
But in my experience, despite having very active and passionate users, the lowest form of interaction always wins out on a free social service. Lack of interactions means user churn - no matter how good or important the interactions that take place actually are.
In that sense, social apps themselves are just vessels for human interaction - and great human interaction happens all over the place whether an app exists or not. Your goal as a venture backed social app is to focus those interactions and try to monetize them.
Is Path going to be one of those handful of "lucky" networks where those interactions happen in large enough numbers to make it viable financially? Personally I wouldn't bet on it.