The question of what might happen if Trump wins comes up often. There are a range of opinions from the literal nuclear annihilation of the world, to nobody even really noticing because so little changes.
I want to take a look at the life of three men, Huey Long, Maurice Duplessis, and Joh Bjelke-Petersen, as possible examples of what a Trump government might do. All three lead sub-national governments; Louisiana, Quebec, and Queensland, and all three were famous for their 'iron fisted' control over said governments, and similar approaches to repression towards anyone who did not fit their view of the 'norm'
Long was first elected as Governor in 1928.
Long was accused of having ties to the KKK, but at the same time, Long could be seen as a progressive, demanding to "share our wealth" with everyone. This is something that happens often with those on the far right, they wrap around the political spectrum, and pop back out on the far left. Political platforms of racialist parties often do have very left-wing policies in terms of social support. This is often combined with the fact that uneducated poor white people are often the base of support for these candidates and parties.
Long not only obtained a stranglehold over state politics while Governor, but he continued to hold it after being elected a federal Senator. Long was often called the closest thing that the US has ever seen to a dictator. One thing done during this period was the weakening of the office of the mayor of new orleans. This is one of the things that is often done by those who wish to crush opposition, by using government power to weaken their democratically elected opponents due to different levels of government.
Long's power was behind the scenes. There certainly was clearly sketchy things done within the press and in legislation, but most of what was done was using regulation and the powers of the executive. This can be seen in decisions as to who to hire, or contract with. This is the much more traditional "corruption", but tinged with heavy elements of ideology. As an example, such a government would hire their ideological friends rather than someone who they disagree with but who could line their pockets with money.
Long died in 1935.
A year later, in 1936, Duplessis was elected Premier of Quebec.
His connections to the Catholic Church are well known, and in fact, it was during this period that the church was seen as opposing the Liberals, implying that Red, the Liberal colour, was also the colour of hell.
One famous piece of legislation made it illegal to disseminate "communist propaganda". Of course, it failed to define exactly what "communist propaganda" is, nor did it allow for a presumption of innocence. It is exactly these kind of law that allow for abuse of power. After all, if you have the power to decide that anything is against the law, what is to stop you from deciding the people you personally dislike happen to own all those illegal things? Thankfully for the majority of citizens in Quebec, the answer was the ethics of the powers that be, but this was not the case for everyone.
Perhaps the biggest difference between Duplessis and Long was that Duplessis was strongly opposed to progressives. He did what he could to develop rural areas, at the expense of urban areas. Duplessis motivation for trampling the checks and balances was to support his view of "tradition" and the existing pro-catholic culture in Quebec.
Duplessis' strength came from his control over legislation, planning, and the official powers of government. While there certainly was a press strategy and movements behind the scenes, much of the 'control' came from the legislature. This made Duplessis' control much more 'visible' than that of Long, and represented an alternative strategy to achieve, in some ways, the same ends.
Duplessis died, from a stroke, while still Premier, in 1959.
Joh Bjelke-Petersen already had a seat in the Queensland legislature by then. Two years earlier, his party had won government, and in 1963, Joh became a Cabinet Minister. By August of 1968, Joh was Premier of Queensland.
Joh lead the Country/National party in Queensland. Normally, in Australia, the Nationals were second to the Liberals. Both parties, being right-wing, sat in a permanent coalition, weather in government or opposition. Queensland, however, was different. Most states had great concentration of populations around the capital. Consider that here in Canada, Toronto and Montreal are heavily dominant in terms of population. Compare this to Alberta or Saskatchewan, where the largest city is not so dominant, or New Brunswick, which is very diffuse. Queensland, while not quite as diffuse as New Brunswick, nevertheless allowed the Nationals, which were always stronger outside that main central area of population, to do very well. As such, Joh, while Premier, lead a coalition with the Liberals.
Joh is famous for his political maneuvers. The National party has always been a bit more right-wing and conservative than the Liberals. Joh governed from the right, and purposefully risked his coalition with the Liberals on many occasions. When the Liberals finally had enough, they broke the coalition in 1983, Joh ran for his own majority, and after a couple of Liberal defections, he achieved it. This allowed him to govern from even further to the right.
When police were caught on TV assaulting a protester by hitting her on the head with a baton, Joh gave them a pat on the back. The protesters, enemies of 'order', were the bad guy. This plays well because the majority of people who vote have never taken a part on any mass demonstration of this sort. They can not identify with the protester, but they can identify with fear. Who is it they fear? Not the policeman, who is their neighbour, their friend, but with the protestor, who is behaving in a way that seems incomprehensible.
Joh's control was in the press. While he did not force opposition off the air, his strategy was one of a showman. Joh used television to gain control not of the executive machinery, not of craftily devised legislation, but to gain control of society and the voters themselves.
By December 1st 1987 the pressure became too great, and Joh stood down as Premier.
Since then, there have been other politicians and parties have have proposed these sort of nativist policies. Donald Trump fits in well with this group. So where does Trump fit in?
Of the three presented above, Trump is most like Joh Bjelke-Petersen. In some ways, Trump is also similar to Margaret Thatcher, and different from Ronald Reagan. Trump's view, to summarize, is that there are two kinds of American. A "Normal" American, who has a job, a family, watches lots of television, and is probably white, and an "Abnormal" American, who sticks to strange traditions, spends their time protesting, and gets all their news from online sources.
This does not provide us with our final answer, but, does provide vital background information to this question.