If the BlueSky protocol offers tangible benefits over ActivityPub, the BlueSky protocol could become the basis for ActivityPub 2.0. I don't know much about the details, though.
I just wish this was a native function of one or both platforms. What a feather in Bluesky's cap to say that they're interoperable with Threads, for instance.
Yes, although the protocol is already open, which I think mitigates the risk slightly. Bluesky is also organized as a public benefit corp, which mitigates the risk almost not at all but is interesting. If Bluesky begins to go the way of Twitter, other corporations or entities can make interoperable replacements easily. That was not so for Twitter.
But in general, yes. This is the same song but a different verse. People have been so blinded by the brokenness of the internet as it is now that an interoperable protocol doesn't make any sense to them.
People on Mastodon are quite vocal about BlueSky, so I doubt that many people switched. I think that BluSky gained its audience from Twitter users mostly.