Very interesting, I'm fairly optimistic on Steem as well, I think it's true strengths will lie outside of Steemit, when a twitter like version is polished and released.
I feel that twitter has the largest set of 'content creators' not already being remunerated, and would migrate over in droves if we can provide the platform. Facebook for the average person is mostly about keeping in touch with friends and family , and Youtube already pays its content creators, so I feel that the barriers to competition there are a lot higher.
Overall I think that a market cap of 1-10 billion is on the reasonable side of optimistic for Steem, but we can always dare to dream bigger.
I agree that twitter user might be the easiest to shift to Steem. I think Redditors would also be quite easy to make the shift. I think it's only a question of time.
I agree the market cap thing is more of a dream than a assurance yet as good as it might look, my mind is set on some other thing than money. I can't deny people are dying over the lack of it and so currently money is a big part of social change I want to see and put my mind to but I try to avoid going insane over money, always wanting more and forgetting the more fundamental stuff of life.