Caroline Glick in the Jerusalem Post has speculated on the consequences for Israel of a Trump presidency plus or minus a British exit from the EU.  Her points are good and can be expanded to more general applications.

1. Trump, by purist definitions, is not conservative, nor is he liberal or progressive.
2. He is an opportunist and not predictable.
3. He's not stupid.
4. He's not sound on economic or political policy.

The good news is, he's not an ideologue (such as Cruz, or the much preferable Rand Paul).  The bad news is that he has no coherent view of the world or this nation's role in it.  One corollary of the four points above is that he may seek out and appoint clever, practiced, sound, well-educated people for positions of leadership within his administration, similar to FDR's Brain Trust.  Another might be that he will be just another tin-horn dictator incoherently careening from one blunder to another so that neither we nor our allies nor our enemies will be able to predict what comes next.  We can hope that he is a fast learner.  And then there's Eisenhower's famous complaint that when he was a general he gave an order and things happened; but now that he was president, he gave an order and nothing happened.

Hillary, of course, knows exactly what she is doing and quite a bit about how to go about it, is a conniving manipulating ideologue, and is therefore vastly more dangerous than Trump.

If we were to choose an appropriate president, we wouldn't have to worry about all that.  But that seems not even remotely possible.  So let's just consider what little we do know about Trump's intentions:

1. Build a 1,200-mile extension to the 670-mile existing wall at the Mexican border.  Vicente Fox has already said, in English, that Mexico is "not going to pay for that f****** wall."  And that still leaves 1,290 miles of Pacific coast, 3,000 miles of Atlantic and Gulf coast, and 3,000 miles of Canadian border free for mostly unimpeded entry.  Not to mention that "The Wall" will be more than a bit less impenetrable than Israel's, which is itself occasionally breached.

2. Start, or threaten to start, a trade war with China and possibly Mexico.  Tariffs are notoriously bad for the initiating country as well as for its trading partners.  The pros and cons of free trade have been debated, studied, and clarified for many years, and many experiments have confirmed theory.

3. Bar all Muslims from entry to this country; close mosques, at least those that endorse jihad el-asghar (That's the jihad where they kill us, not the one [el-akhbar] where they examine their consciences and resolve to do better.), and deny tax-exempt status to Islamic institutions.  A decent argument can be made for this policy, since jihad is essentially a declaration of war, and all devout Muslims could be qualified as enemy combatants.  But it is unconstitutional unless Islam can be redefined as a political rather than a religious organization, which though not unwarranted is not even remotely plausible.  Wouldn't it be nice to be able to prosecute Islam under the RICO statutes?  Even so, it's the religiously devout Muslim who is the threat, not the apathetic.

And then, we know that the moderate Muslim occasionally turns murderously devout.

4. Deport all illegal immigrants in this country, whether with or without arrest histories.  This would deal a serious blow to agriculture, at least in the West and the South, and impair the construction industry.  A reasonable version of this, and indeed highly desirable, would be to deport any illegal convicted of any criminal offense, rather than incarcerating them here or, as often practiced, releasing them to the community, where they can re-offend, especially in sanctuary cities (the San Francisco murder).

One possible plus: Reagan famously succeeded in his Strategic Defense Initiative strategy by subtly cultivating the image of "cowboy," raising the ante on the Soviets.  But Trump may be much less subtle and much more convincing, on us and on others, with uncertain effects.