Anyone care to explain to an American what the situation is with the border?

I'LL BITE.

"but what comes next?"

If there's a no-deal-crash-out Brexit, we'll see the break up of the UK. An independent Scotland, a united Ireland and the rise of a fascist regime in England as its economy is shorn to pieces. Once their Polaris submarines go dark, that'll be all she wrote.

"So do most people favor some sort of reunification or see the north as it's own entity?"

I have to use broad-strokes here: Most people are in favor of reunification. It was a stated goal which we 'physically' removed from our Constitution as part of the Good Friday Agreement but there remains the chance of a 'border poll'. Depending on how badly Brexit goes, a majority of people vote for unification, like this:
a. Catholics on the island are generally in favor.
b. The Protestant population North of the border would have staunch unionists (they want to stay in the UK no matter what).

"What sort of things do you predict if the hard border becomes a reality?"
A border poll would be likely after a few years as the UK economy gets picked apart. Unionists have been telling Catholics in the north to leave Northern Ireland and settle in the South if they don't like it. And that's what they've been doing, for generations, without much fuss. In contrast, upon Unification, it will be the Unionists turn to hear that suggestion. The problem is staunch unionist traditions do not exist in places like Leeds and Manchester and London. They will have problems integrating with that population because they are, more than they care to admit, Irish. They will be homeless and barren.

And how would you like the situation to play out?
I'd rather see the UK stay in the EU than a united Ireland.
Look, the Brits need to make a choice - do they want a united kingdom or a united Conservative Party. Only cancelling Brexit can guarantee the latter. Only a No-Deal-Brexit can guarantee the former.

/r/ireland Thread