As time goes on more users who contribute to the system will be rewarded more steem power, And their upvotes will distribute wealth to more content. Eventually there will be more 500$ posts and less 25000$ posts.......
There will be some hudge volotility for a while on steemit until the user base grows so much that the distribution of wealth is slightly more fair(whales cashing out, Newbies getting upvotes)
Last week i couldn't add even one cent of value, Now I can :]
RE: Long Term Sustainability