He's not moving anywhere and any Twitter controversy gets more people to tweet about that controversy... Until he forces a significant part of his followers to leave, it's not a bad situation for Twitter to be in.
Or worse, in terms of discourse. I suppose twitter is awful for something as complex as political debate, but removing an entire half of a political spectrum would only serve to further divide our country, something which the real demagogues of the world would love to capitalize on.
I would suggest that maybe Hillary Clinton's campaign and candidacy alienated many people in the center. In my mind, that seems to be the simplest explanation for the existence of Obama-Trump voters.
I think the Obama-Trump voters were a result of 8 years of partly empty promises. (He did a lot, but people hoped for much more. Yes we can / yes we scan.)