Ok, as an American, here's a serious response...
The Democrats did not leave when Bush was re-elected, the Republicans didn't leave when Obama got in. No one is moving as; 1. they can't just walk there, 2. talk is cheap, immigrating isn't (I know I've move internationally 4 times, if there ain't a good paycheck to go to politics is a poor reason to pack up and go... unless you live in Syria, dying in a bombing is a more compelling reason to immigrate than a bozo as president... which is kinda the norm lately...
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I think it would be fantastic. (and I am a life long Democrat, and am not a supporter of Trump other than to say "let the public decide" and anyone who want to run should be able to)
As a total outsider it would be pretty much unprecedented... the reality is that the professional bureaucrats in Washington would circle the wagons in Congress, as the Republican Party is now doing as they have finally twigged to the fact he has a real chance, and he would probably get nothing done. The president has power, but it is checked by the legislative and judicial branches of the triad of US government. Look at Obama's inability to get much done. And Trump would have both sides against him, not just one! Doomed.
It is lens on the dissatisfaction of the majority of the Republicans, that the status quo has failed to achieve the goals of the rhetoric. On the positive "The Donald" won't kow-tow to the radical right and evangelicals, which is the downfall of the Republican party and why Trump is doing so well. In order to get elected the party heads had to keep going further and further right to maintain that vote, as the margins of victory are percentage points. The evangelical wackos stay home then they lose... so they alienated the middle. And Mr Trump is pulling the disaffected middle in to his camp. So in some ways a positive and he is not as beholden to the far right (e.g. put religion in politics, very dangerous) as the "traditional" GOP candidates. Similar for the Democrats, have to defer to the fringe left, similar result, but not quite as extreme.
He's really no worse than Dubya or Obama... both inept. All have agendas and the gridlock in US politics would keep even God from making any significant change in America as president... And Hillary is a rehash of the past 30 years. Same old same old... an uninspiring and completely bland alternative.
And recently he has been talking "compromise" which is anathema to most Republicans or Democrats. As the goal for the last decade plus has been to, on principle, oppose anything the opposite side presents, even if you agree with it. Total incompetence, and maybe Trump is a way to drive a real change in US politics and without one the future is just more of the same... the rich get richer, the middle class gets squeezed out and the politicians really do nothing to make any significant changes. Just ensure they stay in power to get rich (on both sides). But Trump will support business and the rich, no doubt.
Even when something is passed, like Obamacare (a good idea, horribly implemented) the political obstruction makes it doomed to failure, as the goal is fight the other side, not make it work. Keystone pipeline is another one on the left, they oppose it on principle, yet have approved dozens of similar projects during the same time... political football with no reality but the media plays into their hands to show they are "environmentally sound" to support the left vote. If "mini Trumps" follow him into the congressional arena, maybe hope for change... maybe...
If Dubya never launched, Trump is nowhere near the "fer us or agin' us" war monger to support political views (and his/daddies Halliburton buddies via Cheney, now that was one evil prick) Bush II was. He has noted the Iraq invasion was a bad idea and that the way Afghanistan was handled was poor, so I don't see him as as much of a hawk as many Republicans. Look at Cruz, "lets carpet bomb the Mideast"... yes Rolling Thunder and Westmorland's "bombing them back to the Stone Age" worked so well in Vietnam.... brilliant "new strategy" but playing, successfully, to the simpletons...
And to me it has to be a good sign that both the Democrats AND Republicans are saying he is a bad idea.. if the status quo is aligned against him it tells me he's onto something they fear... change and talking their grip on power away!
Besides, his winning would show how stupid most Americans are, as they are voting for hot air and blather that anyone with a brain would know just are not going to happen... "feel good" big talk get folks all excited, but the fiscal and political realties of implementing a lot of the flag waving "we'll be great again" is "get elected blather". Politics is dead, this is pure populism (which does win elections, but rarely provides real long term solutions). But he is already toning down a lot of the rhetoric/issues as it seems he sees a potential to actually win. Moving towards the middle even more, which should scare the bejeezus out of Hillary.
But if he wins, I'd bet 3 years in not much will have changed and they'll be looking for the next simple solution to a complex problem and he's out as a one term wonder... the public would not be happy with their choice and majik changes will not happen (19 trillion in debt and a weak economy with a thin base is not going away overnight!) then we probably get Romney, Cruz, Rubio and Clinton again in 2020.... inspiring....
On the other hand, he could implode in 2 weeks and evaporate. Bernie could pull a miracle, and he's just as funny to think of as President as Trump... November is a long way off.... at least its entertaining!
Really the biggest issue, besides if he wins, is that this could be the death of the Republican Party in the US as it has existed for decades... fractured beyond repair. Potentially a huge shift in the two party system that has ruled the US for well over a century. That would be a significant and long term change that would be interesting to watch. How the GOP moves thru this in the future will be interesting to see.
