I'm not claiming to know what reality portends, but I do think my guess is about as good as anyone's.

Bluesky did something ActivityPub/Mastodon never did, which is reach a mainstream audience of non-technical people. But its growth has been severely limited for one reason: the network is niche and uninteresting to most people.

Communities are a potential solution to this problem. If they work, it is plausible that tens of millions of users reactivate and, eventually, hundreds of millions of people join the network.