I think that Steemit is not going to kill Facebook in near future. Steemit is going to be a very strong player for niche audience. At this point it is very hard to tell how it is going to grow. Just because I'm new to Steemit and am not very familiar with the creators.
For what I'm sure - blockchain is our future.
Good point, however see my older posts for reasons why steemit will be very successful including tips to be more successful here