It says everything about the tone of this four-year posting in the United States that the President is likely to be impeached literally as I'm on the plane back to Australia.

It's been like living in a reality TV show with endless climaxes.

It also says everything about the situation we're in that the impeachment of the President will, in the end, be just one of a thousand "wow" moments during the Trump administration.

In fact, there have been so many wow moments that almost nothing is wow anymore.

All benchmarks have shifted

When the scholars come to write the history of this era they will say something like:

"In the winter of 2020, Democrats tried and failed to remove Donald Trump from office by impeaching him. The Senate refused to impeach the President, and he duly went on to win his second term in November of that same year."

They'll go on to say something along the lines of:

"The impeachment came at a time of deep partisanship in US politics, with Republicans accusing Democrats of a politically motivated witch-hunt and Democrats retorting that Republicans were the enablers of a leader who abused his power and won elections with the help of foreign governments."

As soon as Zoe ventured to states like Iowa, it became apparent to her that Donald Trump's rhetoric hit home with many Americans. ( ABC News: Brad Fulton )

When I was appointed US Bureau Chief in mid-2015, Hillary Clinton was strongly expected to win the 2016 presidential election.

Mr Trump had already descended the golden escalator to declare his candidacy, but he was viewed as a clown, his run a mere sideshow that would surely falter. At least that was the view from outside the US, and from the big, liberal cities here.

But as soon as I hit the campaign trail for the Iowa caucuses in early 2016, I got an inkling that things might not play out quite the way everyone expected.

Mrs Clinton was being seriously challenged by renegade Democratic Socialist Bernie Sanders, and Mr Trump's message was resonating with voters outside the urban centres who were looking for an anti-politician to shake up the deeply entrenched Washington establishment.

Candidate Trump started the way he planned to continue

With deeply divisive rhetoric, and an anti-PC approach that's validated racism and sexism, ultimately changing the way that Americans treat each other.

In that search for a political leader who would speak their mind, Americans found someone who has shifted the lines of civility.

"When Mexico sends its people, they're not sending their best," Mr Trump said on that first day at the bottom of the escalator, when no one thought he would win the election.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 47 seconds 1 m 47 s Donald Trump accused Mexico of bringing drugs, criminals and rapists into US during 2015 presidential announcement speech

"They're sending people that have lots of problems … They're bringing drugs, they're bringing crime, they're rapists. And some, I assume, are good people."

In that first speech that kicked off his campaign, when he branded Mexican immigrants criminals, Mr Trump changed the public discourse.

His election rallies thereafter were filled with supporters chanting "Build the Wall", and much of his popularity to this day is built on inflammatory dog-whistling about immigration.

It syncs perfectly with the backbone of his pitch to voters — that he's a CEO who's driving the economy while saving jobs from foreigners.

After all, 'America First'

The President employs deliberate chaos theory in the way he goes about running the country. In doing so, he keeps everyone guessing and almost entirely controls the narrative. It's difficult for anyone — be they politician or press — to run their own race when they're constantly running after someone else.

Saying outrageous things is one way of keeping the spotlight and Mr Trump has exploded the limits on what a politician can get away with.

On TV host Megyn Kelly after tough questioning during a primary debate:

"You could see there was blood coming out of her eyes, blood coming out of her wherever […] I have no respect for her."

On US District Judge Gonzalo Curiel, a native-born American, who was hearing a class action case against Trump University:

"He's a Mexican. We're building a wall between here and Mexico. The answer is, he is giving us very unfair rulings — rulings that people can't even believe."

On the late senator John McCain:

"He's a war hero because he was captured. I like people that weren't captured, OK?"

On Muslims:

"Should I read you the statement? Donald J Trump is calling for a total and complete shutdown of Muslims entering the United States until our country's representatives can figure out what the hell is going on."

On white supremacists, after a woman was run down and killed during a race rally in Charlottesville, Virginia:

"I think there is blame on both sides … You also had people that were very fine people on both sides … Not all of those people were neo-Nazis, believe me. Not all of those people were white supremacists by any stretch."

Can you imagine any other politician getting away with any of that?

Donald Trump did.

At the start of the 2016 campaign, he called it

"I could stand in the middle of Fifth Avenue and shoot somebody and I wouldn't lose any voters, okay? It's like, incredible," he said.

Even a leaked Access Hollywood TV tape in which he was overheard talking about grabbing women "by the pussy" failed to sink his campaign.

Chaos theory applies to his approach to policy as well.

"Keep them guessing" sums it up.

Is Russia an ally or a foe? Is NATO stable? Are we headed for a global trade war? What happened to the idea of a world climate change pact? What about Syria, Iran, Iraq, Afghanistan? Is nuclear conflict with North Korea imminent?

Remember "little rocketman"? That was a rhetorical high point to be sure.

Loading

All of this has been closely observed elsewhere.

The likes of Rodrigo Duterte in the Philippines, Jair Bolsonaro of Brazil and several European leaders have weaponised Trumpism. Even Australian leaders have loosened their language to appear less PC, more "of the people".

Of course, inconvenient truths are now routinely denounced as "fake news", a calculated strategy to undermine the news media and weaken its capacity to hold the powerful to account.

And under Donald Trump, it's a new, uncertain world order

On election night 2016, I was at Mrs Clinton's event in New York. It began thick with excitement and turned into a wake when her supporters realised that she had lost the election.

I wasn't surprised.

I had spent a year talking to Mr Trump's supporters, hearing their anger about job losses, immigration, failing infrastructure and Washington largesse, and their fears about the future for their children.

Zoe spent election night 2016 with Hillary Clinton supporters, who were shocked and tearful. They missed the signs. ( ABC News: Brad Fulton )

Many of them didn't like his rhetoric, his treatment of women, his tweeting, but they were prepared to tolerate it for the sake of a leader who was more direct, who was prepared to shake things up, to shift the status quo.

While Mr Trump's events were rowdy affairs attracting thousands to fill basketball stadiums, Mrs Clinton would meet a couple of hundred on a high school basketball court.

He had the momentum, controlled the narrative, stole the limelight. He still has it.

"I feel like our country has been taken over by aliens. Who are these people?" one of Mrs Clinton's supporters said to me tearfully, late on election night.

Three years later, with another campaign about to launch, Democrats are still asking that question.

Until they figure it out, the world order will be Donald Trump's.

Every reality show needs fresh talent now and again. The next season will be directed by the new Washington Bureau Chief David Lipson, who will bring you his analysis here each week.

With thanks to the ABC's Washington bureau team for an incredible four years.