No I don't think that steemit.com is going g to be the next Facebook.I think it has the technical aspects to even surpass the Facebook.Although it's a very long road but steemit can make this possible. When Facebook was launched their their was no competition to its product , no other company even came close to challenging it's monopoly.
But in steemit with the block chain technology, a very robust reward system and it's users so dedicated that they are bringing in new users very day there is a very a very good chance that steemit can be the next generation social media platform connecting the world