Perhaps the single greatest challenge in this will be the process of shaking people out of their apathy. Giants like Facebook and twitter have "trained" the vast majority of the world to believe that the "standard" for how much effort one needs to put forth to participate in any given activity is called "log in with Facebook."
Therein — for example — lies one of the Hive Ecosystem's great challenges... it's not "plug and play" in the sense most people think of it. LeoFinance comes as close as any, with the ability to create an account with twitter information... but that still ties someone to the very thing blockchain is trying to get away from.
Not saying I have any great solutions here. And I'm not sure where it leaves us, either. Trying to "poach" the people who are closest to being fed up with the giants? Or trying to create some some standardized blockchain based "Open ID" type facility for individuals, so you essentially only create an account that subsequently can verify everything you sign up for? But then... that reeks of centralization, again.
A challenge, to be sure!