There seem to be a shift in power in social networks where not one social network is a clear number one. This is mostly due to the fact that each social network brings something unique to the table, thus comparing becomes hard Twitter and Facebook are both social networks yes, but are they the same? Hardly

Expanding without touching the creative side of Steemit will indeed be the big challenge. I am not fond of the referral system as it promotes cheating with multiple account. The witness program is something I can't really say much about, as I lack the basic knowledge. But as it seems more a popularity contest which heavily favors the early users it isn't something that really peaks my interest. Giving 20 people some power over a million is just absurd from the beginning.

For me the biggest challenge seems to be not finding new members, but rather keeping the new members motivated. After the first introduction post which often gets a lot of response and upvotes the majority faces the harsh truth that most of their work won't be noticed by anyone no matter how good the quality is or how much effort they put in it. You can't keep someone like that aboard nor can you blame them that they quit.

I'm not half as experienced with Steemit as you are but I know for a fact the biggest truth here lies in: "either we will change or somebody else will make a better project". I just fear that the people capable of the biggest changes on Steemit are also the people that are the least willing to do so