Maybe steemit won't do it, maybe it will. We will never know until it happens.
And this is something we all need to understand: Steem is not about steemit. Steemit is just a platform that creates a real use for the cryptocurrency steem. Maybe the next big social media that rivals facebook will be created in one or two years using the steem blockchain, but it won't be steemit.
That said, I can see that steemit has a huge first mover advantage and a fast growing community, so it is very well positionned to be that revolutionary social media.