1. The Nightmare. A wild man who offends all our allies and enemies and everyone else and declares war on Kyrgystan to punish it for being too hard to spell.
2. Promise Keeper/Paladin of the Right. Trade barriers up, immigration down, many illegals expelled. Everything the government was doing that offended his base, from restrictions on burning carbon to pressuring colleges to lower their standard for convicting students accused of sexual assault, cancelled or reversed.
3. Virtuous Traitor. All the bad ideas on immigration and trade either retracted, forgotten, or deliberately proposed in versions Congress won't pass. All the good ideas–school vouchers, reduced regulation, legalizing interstate sales of health insurance, replacing Obamacare with something that works, simplifying the tax code–implemented.
4. Hillary+. Lots of ideas the left likes–increased government spending, increased borrowing, free colleges, student loan forgiveness–implemented with the support of most of the Democratic party and parts of the Republican.
All of these are possible. The first is less likely and the last more likely than most commenters, especially on the left, think. The belief that Trump is crazy is based on his performance during the campaign, repeatedly doing things that would obviously result in his losing. Since they resulted in his winning, one has to revise that judgement and consider that perhaps he is crazy like a fox.
The belief that he is a right winger is also based on his performance during the campaign. There too, the fact that it worked suggests that his positions may have been tactical, not ideological. We do not know what ideological beliefs, if any, he actually has. Things he has said in the years before are at least equally consistent with viewing him as center left.
That is half of the argument for the final possible Trump. The other half is George Bush. Bush was elected as a conservative. He proceeded to sharply increase spending, the deficit, and government control over education. Spending money is generally popular, lowering taxes is generally popular, and there are usually political points to be made by "doing something" about whatever people at the moment want something done about.
My guess is that the two least likely outcomes of the election are the first and worst and the third and best.