Twitter's unbanning of an alt-right loony provides a pretty good indication of how they deal with high-profile account holders. (And Milo the psycho/troll, too.)
Basically, Twitter is a product with a license agreement. You follow the rules, you keep your account. You break the rules, you lose your account.
I honestly think that Twitter will cease to be a thing anymore in about 12-14 months. It'll go the way of MySpace. Twitter was already pretty much completely irrelevant by the beginning of last year (2015), due to being heavily gamed and almost entirely populated by bots. Then Trump happened. It's the last gasp of a dying form, when the only thing your platform is good for is the lunatic fringe.
Here's how it will go down: Trump will incite some sort of riot or "event" on Twitter, which will require Twitter to ban his account. He will come back on with a POTUS account, and - being a man-child - get nasty and bitter and double down on his inciting posts.
Twitter will hem and haw for about two weeks, and then be forced to ban the POTUS account for failing to adhere to the T's & C's.
Twitter stock will crash. The alt-right whackjobs will flood it with so much garbage and shit that it will drive away the last few actual human beings on Twitter, and it will slowly fade into irrelevance as bots retweet bots retweet bots retweet bots.
Something like Buzzfeed will buy the IP for, like, $15m, and try to wrap it into their media empire. It'll fail after 18-24 months, and the final articles about the Twitter platform closing down for good will be written by a NYT journalist who started using Twitter in elementary school.
But nobody will read the article, except to marvel at how far technology has come since Twitter.
Overheard in a bar later that month, "And gee... can you believe anyone actually used a service called "Twitter", at all? It's just such a stupid name..."
For further reading see: MySpace, Tribe, WebTV, Compuserve, YahooMail, etc.