I believe we probably will see a Facebook alternative on the STEEM blockchain but it will not be Steemit. Someone is developing that application somewhere in the world. That is the beauty of blockchain. Steemit will be a Reddit competitor especially with the communities upgrade.
Blogging will be a big part of this blockchain but, again, we might find the payout is in a SMT. Even on Steemit, we most likely will see a shift to a SMT for bloggers.
STEEM is going to be the fuel for the blockchain. And now that it is a funding mechanism, I foresee it becoming even scarcer.