Facebook won because it mapped the real world's social graph onto a virtual social graph. If a product is to take Facebook's throne, it will need a similar hook. Beyond that, it will likely also need to position itself as the "anti" facebook - no tracking, no data collection, etc.
Not saying this isn't important but outside of here and other niche communities, regular people show no signs of caring about this.
most people are content with the way things are, not really feeling the need to 'reinvent the wheel'.
I agree with you there, I think that is why all the other challengers have failed. None could create an equal social graph or off anything good enough to make people want to leave.
By now though, it may be the case that people don't want to join anything new because of losing 'memories' and fear of missing out.
It'll be what makes the entire point of the original service completely obsolete.
Is the social space the same as search engine space? Google and Facebook's advertising tentacles are growing stronger every quarter too.
It's all speculation though. We can rule Microsoft out.