If the Musk purchase does not go through I think there will be a mass exodus event at sometime in the fairly near future. I don't know where everybody will go, but we are seeing a creeping exodus away from Youtube to Rumble and Odysee and others.
It's easier to walk away from Youtube because people follow links to a video on Youtube from outside or they already know who their favorite people are to watch and easily follow them to a new service.
Twitter is not so easy. The conversation is on Twitter, both with people who follow you and people you are trying to persuade. But if enough interesting people dual-post or migrate over to another service, we could achieve critical mass and have an exodus. Then the censors will have nobody to silence but themselves.
Musk would be better served not buying Twitter. The vast majority of the employees are so incompatible with his vision that he'd have to fire nearly all of them. There would be nobody left to turn out the lights! And someone would probably find a way to sabotage the system on the way out.