This is a question that I've been asking myself and so far don't have an answer.
It ties into your other post about some users gaming the system.
There are quite a few problems with this site that would prevent it from becoming as popular as something like Facebook.
It's still too hard to use for a newbie.
The bots thing is murky and seemingly unfair.

There also isn't a decent way to search for topics or users here.
We'd all need to be able to build, cultivate and maintian our own audiences to be able to rely purely on Steemit for income.
The central idea of content backed by a cryptocurrency is something that we migth see being copied elswhere.

Maybe for media there will need to be a mixture of revenue streams?
Some from crypto, some adverts, some subscribers, some donations.
More of a mixture and a more diverse base than exists currently.