Some people will never leave Twitter because it's familiar, they're an established journalist addicted to feeling important, or because they're right-wing chuds who want to see Musk and Truth Social Redux succeed.
Some will migrate to Bluesky for Twitter without Musk. Some will stick with Mastodon on principle or because it's good enough. And then there's some also rans. But I don't think Mastodon or Twitter are going anywhere anytime soon.
Twitter's entire problem is Elon Musk, the debt he saddled the company with, and the intentionally awful decisions he makes. But it still has the most users and is by far the easiest to directly monetize.
That may relegate Bluesky and Mastodon to niche platforms for people who want to avoid ads and other shit. And that could be a lot of people! But it may never dislodge Twitter from its current place of importance.
Only Musk can fly that rocket into the ground.
In the meantime, Bluesky is going to get attention because people are attracted to a shiny new thing and frankly, most social media users don't want to think that hard about what platform they're on.
The people who will leave Twitter typically want the alternative to be extremely Twitter-like, easy to use, with big names they're familiar with, and preferably slick to look at.
They don't care about decentralization or who owns or controls what.
That's neither good nor bad, but it reflects the fact that the average Mastodon user doesn't care about replacing Twitter and is often opposed to making it more Twitter-like, culturally and technologically, even it means driving potential users away.
Bluesky, meanwhile, is very specifically aimed at people who want a Twitter replacement, even if it's not there yet.
Regardless, this could all end with Twitter winning by default, with all of the negative political consequences that entails.
Nowhere Girl
Jeffgodofbiscuits