Theyll see no effect of their speech, and try something else. Like voting, protests, and violence. In thay order
This is touching at the debate of "should social media be regulated or treated like the commons when it gets so large?"
You have a single company with the power and size of a country. Humans were never intended to be using something privately controlled with such an expansive reach & power differential, and then be told "they're private, if you're banned go elsewhere" except well this could be more like a public resource when it becomes that large. We haven't found a good answer to this in a capitalist system because the solution is non-capitalist.