Steemit has the potential to became the best "social media" easily, and as we can see, we are on a good track to achieve that in the next years.

I, personally, don't think Facebook will die, because they are very good adapting to the world always changing, that´s why they are the best at the moment. So, Steemit won't be the Facebook killer, but it will definitely kill a good amount in their profits, because while they have to study this new technology, Steemit is already founded on it.