I think ActivityPub and Mastodon are alright, but I think a thing that looks and behaves more like Twitter will be more successful at succeeding it than something that doesn't.
I get that Mastodon people are salty about Bluesky. Personally I was hoping Elon Musk buying Twitter would be taking the Jenga piece that collapses the social media tower. But this is how nerds vs capitalists goes, unfortunately, and my evidence is all the walled gardens that sprung up in the fertile pre-web-2.0 internet.