If you ask TBL what Web 3.0 is, he'll say it's about sharing data rather than documents or apps representing that data. That never really gained mainstream excitement (rather a slow but sure growth), but it'd certainly be part of your concept of Web 3.0.
And his formulation of that is certainly a part of ActivityPub.
But I don't know what'll gain adoption next, yet I will be throwing stuff at the wall to see what sticks.