The political groups are simply rough mappings to "major demographics" of users and their preferences - clout-seekers, self-styled entrepreneurs, collectivists. The actual shifts taking place are all within the old bundling/unbundling saw: some features are now outside of the product, and some are integrated into it, and the features attract or repulse these demographics accordingly.

Mastodon always presented some dealbreakers for the "clout-seeking" demographic, since ActivityPub doesn't flatten the space into one high school class ranking(basic KPIs for this goal like numbers of likes don't synchronize across instances), and instances that behave badly are treated by the broader network as "nails to be hammered down", for better or for worse. And nostr likewise centers visible exchange-of-value which is too grubby and nakedly commercial for the upper crust. So I agree that Bluesky is "it" in the realm of attracting Twitter users, for the moment.

But any of these three could absorb features of the others in time. That tends to happen in tech.