> I think his plan B will be to start a competitor

I hope it isnt: I think that starting a top down, meaning "look I built this, everyone move over from twitter", competitor has a very low probability of success, regardless of who starts it. There is too much of an attack surface, there will be too much drama on real Twitter about it, early adopters will be gun nuts or some other out group and that will be how they get characterized, etc etc.

The real chance at a competitor would be something that grew organically, that people wanted to move to because it offered something valuable before it reaches scale. This is how actual businesses start. The top down approach is how massive flops happen.

Incidentally, the same holds true for the Facebook metaverse and imo suggests it will certainly fail