I think you are even underestimating the potential. Facebook, youtube, blogging sites, and others get the majority of their income from advertisers and it amounts to $trillions in market cap.
I think adding promoted posts as a sidebar rather than separate section would increase the benefits for those users and would attract more advertisers.
Also Dtube needs to be seamlessly integrated. Is that part of Steem?
RE: If you are invested in Steem, you need to read this. Let's make this platform exponentially better.