Clay Shirky on communities, and the ones that last:
You will make more accurate predictions [...] if you ask yourself not “what’s the business model” but rather “do the people who like it, take care of each other”. That turns out to be the better predictor of longevity.
Businesses with brilliantly clever business models die every day. While a business model is important, it is not a predictor of long-standing success. When you combine a sane business model (and a willingness to thoughtfully modify it over time) with a community where people take care of each other, the end result is a 1-2 punch of sustainability for both the business and the community.
Watch the entire 10 minute talk on Youtube: