I'll never be entirely sure how long Steemit is going to last, but I think it's similar to what Andreas A. says about Bitcoin - the cat's out of the bag; this technology is here to stay, regardless of if the individual platform succeeds or not.
One thing that I'd like to see someone create in the near future, is a platform similar to Steemit or based on Steem, that is something like Sourceforge or Github... Open source programmers immediately have an easy way of monetising their work, and perhaps dedicate themselves to it full time, pushing software forward in exciting ways.
Looking at the price does seem a little scary at times, but I guess it doesn't matter much in the long term. The community is still here, and so it makes it very unlikely the price will go to zero. And even though the Steem price is similar to before July 4th, the market cap is from 3-4x. We'll see what happens... I'm wondering whether Steem Power will be my retirement or just a fond memory of a time involved in a new type of online community.