If I were to redesign facebook how would I do it

Facebook used to be one of the best most efficient way to keep up with old friends, and find new ones, but not anymore. With high school students, and people too old for the original age group of facebook, it has lost it's appeal. The fact that I overhear discussions from high school and middle aged individuals discussing the latest gossip they have read over facebook takes away from my once admirable perspective of the website. It has turned into a generic social site like "my space" where you never know what you will find, and chances are probably wont like what you see.
Originally facebook was for college students only. This allowed people to find other college students of similar age and demographics. If I remember correctly, I believe that you had to have a valid college email to register for the site. This created a social network with a common core culture that is no longer there.
If I were to redesign facebook I would make it much more exclusive by finding social demographics that individuals could relay around; age, location, career, politics. This would create a niche market for all users, wile keeping common individual characteristics as a requirement to be registered for that branch of facebook. For example, I would have Facebook Teen, College, non College individuals, middle aged parents, retired individuals all clustered into their brackets so that they could know who they are talking to, and not have access to individuals in another bracket without permission. For example a mother could not spy on her daughter at college without her knowledge, and a old man can not see/ interact with a young girl categorized in the "Teen" Facebook.