Steemit can’t be sustainable in the long run (unless they find revenue streams from advertising) here is why:

Steemit is paying you for the content generated but who is paying Steemit for the content?? The response is Steemit takes the money from other (new or old) members to pay you. This system works only if the community is growing. Once the community gets mature enough there won’t be fresh money coming into the machine and this is when things get tricky…

Think about this scenario: Steemit just released his social network platform. The platform is composed of 2 users. The 2 users haven’t put any of their own money into steem power and steemit has not done any ICO. When the first user ever on the steemit community posted the very fist “content”, how could steemit possibly pay him for the published content? The only way would be that steemit pays the publisher from his own pocket by speculating that other members will start put money into Steem one day…