That's a bit of an exaggeration, don't you think? "Horrifying consequences...abject fear...man enough..." That's quite a bit of twisting you have to do to change my mention of "problems," into making me seem like a fearmongerer. But I understand why you have to do it....
The biggest problem I see with open borders is, simply put, allowing any and all into the country will overload our system. Welfare, education, employment - we already have problems with this. An influx of unskilled labor will make it worse.
They're also consumers. They buy products. On average, they're younger than our aging population, changing the social security equation that is already plaguing us. They're also no more likely to be on welfare than anyone else (actually less likely).
If teachers are in demand (education complaint) then teachers get paid more, that's a good thing, I think. It would mean that the job is actually worth going to college for again. If worse comes to worst, we have the technology for distance learning classrooms (home schooled, but by professionals) to gradually replace actual public schools. It's just a matter of time before we end up going to that anyway. The fact that it would be so much cheaper pretty much demands it. It also takes care of the fact that different kids learn at a different pace if done right. Child care costs would be the new problem here, of course, since elementary school is also a form of child care. There's probably solutions there too though (a higher wage at the bottom would help). If nothing else, child care doesn't normally require a 4 year degree at a university... so again it's still cheaper to go the tech based route and ask parents to do the education supervising, even if the government is still paying for/subsidizing child care and sticking its nose in occasionally (Once a week maybe? Once a month?), especially when there's problems.
Education could go any of several different ways, actually. It'll evolve on its own, with or without immigrants. according to society's needs (and yeah, I'm not sure my ideas would be ideal either). When there's an actual need (and even when there isn't), we'll have no shortage of ideas in terms of ways to deal with it I'm sure. I'm thinking we aren't moving ahead quickly enough as it is. Added pressure might actually help to speed up the process.
Basically, adding more to the bottom only raises the others already here up. Economically, it all takes care of itself, and what doesn't take care of itself can be compensated for by targeted change. Weirdly, the free market economy desired by the same people wanting immigrants to stay out takes care of most of it. There may be an extra little wobble here and there, but it's hardly an imminent disaster.
Change is always imminent, and it's better to embrace it than to fight it, especially when fighting it is a losing battle that nonetheless costs more money.
