I think your logic is circular and there is very little bases to access the demand for steem.

You can say that people will want steem so that they can post on steemit, but why would you want to post on steemit instead of other social media platforms?

You can answer that question by saying that there will be demand to post on steemit, because you can earn steem. But if there is little demand for steem, then the steem you do earn from your content and curation won't be worth enough to incentivize you to post on steemit.

The fundamental problem I have with your argument is that you assume that there should be demand for steem, or even bitshares for that matter, because it is necessary for a user to have these cryptocurrencies in order to utilize the blockchain services. However, you don't provide a compelling answer for how these blockchain based services provide greater utility than their competition.

I hope steem does catch on. I just don't see it having any value if not directly tied to some revenue stream of steemit, because right now the value proposition of steem is very dubious.