I don't know too much on this topic, but I'm working in Cheonan, and I've broached the topic with my co-teachers before.
I have one co-teacher that is a contracted Native Korean, but I think...Well, to hear one full-time teacher put it, contracted teachers aren't very welcome by the full-time teachers. I think the contracting of teachers is mostly to give jobs to recent college graduates? (At least, that was one co-teacher's opinion; I'm just going off of that.) I've heard that that program isn't expected to last long, as it's creating a bit of friction with the full-time Korean teachers. But, as to our positions...I think we're about as safe as we've always been, for the time being, at least.
I do think that, ideally, Korea would like to phase out native English teachers, but...I cannot say when that would be. Programs in secondary education may come and go, but...there is still a great deal of work we could do, I think.
Whatever the case, we are here just for a time. So we may have to leave Korea. That's inevitable, unless you've married/found a lasting employment here; it's just the way of life. And I'm sure that other viable teaching positions may exist in other countries. Don't freak out too much. ^^