We are at most, a few months away from apps with content and sharing mechanisms just not possible on Twitter or other centralized, closed-source platforms. That's when the momentum will really start to build for Activitypub and other protocols supporting federated networks. We have stop talking about it being a twitter "alternative" and start talking about is as an evolutionary step forward in global social networking. Because that's what it is.
When you can get content and engagement here that you cannot get there, that's when we'll shake things up and the old-school twitter model will start to feel stilted and dull.