My view of the Steemit business model is that essentially it comes down to charging people for granting power over the media (using 20th century terms).
Money goes into Facebook because people pay for adds. Money goes into Steemit (people buy Steem for their BTC) because people want to power up to vote on content. Do they? This is Steemit's biggest challenge:
Will people keep putting money into it in a pace that is sufficient for the system to generate enough value to properly reward content creators. If the answer is positive, Steemit is a mind bending genious paradigm shift.
Advertisement is indispensable for business. But is voting on content? Power over content is like control over the media - it has a price. People paid millions for control share packages in news corporations for various reasons. In the 20th century having money alone was not a guarantee that a certain message will be presented for the public, in particular a controversial one, politically incorrect etc.
So my guess is that the Steemit has a bright future because of other factors than just purely financial ones.