It's entirely possible that a fediverse platform emerges that's capable of performing many different kinds of activities. But, the far more likely outcome is that platforms eventually implement the Client-to-Server half of the ActivityPub protocol, which currently very few platforms implement.
The idea is that virtually every Fediverse platform could, in theory, act as clients for one another, enabling a "one account posts everything" possibility with different frontends accessing different subsets of data.