I think Steemit is a direct threat to Facebook and YouTube, I'm sure advertising on these platforms will work, at least for now. However with YouTube censorship it may not last too long before they a stance against Steemit. I already see a lot of Steemit vids on YouTube and I am surprised that Google did not take a position against it yet. YouTube is on its way down, while Steemit is... well picking up steam!! The same goes for Facebook, personally I am not fond of it, even though I do have an account. As Steemit ads functionality and it gets better will take over to be the multimedia/social media platform of choice.
Steem on my friend!!