@peteratmsr Consider the strong possibility of a scenario in which Musk and/or Twitter declares bankruptcy and the site is auctioned off. In that scenario, there are only three bidders who could plausibly pick up the pieces: Google, Amazon and Microsoft.
There are others with the technical means but it is unlikely to be a good fit. I doubt the site is worth $5 billion at this point and it is likely to end up selling for a tenth of that. See what happened to GeoCities after Rupert Murdoch.
I think there is plausibly some value there, but it would be in turning Twitter into a Mastodon/Fediverse site like AOL and Compuserve ended up becoming Internet service providers.
The Fediverse will have end to end secure communications very soon. There are multiple teams working on it. I have been developing a PKI that can move private keys across devices for six years now and had an alpha release earlier this year. WebRTC does all the heavy lifting for Teams, Zoom, WebEx, etc. etc. All we lack to bring it to the Fediverse is presence.