Good qestion, but till than, Steem will be a big platform, and later, if Facebook creates own Blockchain, Steem will not disappears, if Steem developers still being active to make the Steem platform better and better.
And Facebook on the Blockchain will be also good for all of us, that means the Blockchain is getting bigger and bigger, many more people will begin to understand Blockchain and Crypto's and invest in it.
Yes exactly. It will be good for everyone once the large mainstream masses finds out about all of this. Since we don't have the megafone to inform the herd!
Indeed, you got it! :)