Personally, I don't think open borders are unthinkable, but I am not necessarily for them either.
However, the deportation process must be humane. You can detain people who are to be deported in conditions that respect their human rights. You can allow parents of small children with US citizenship to take their children with them (assuming both parents are deported), or to make other arrangements.
The two alternatives are not (1) open borders or (2) concentration camps for illegal immigrants.
Sure, and I think you can get most people on board with the principles of "people in deportation holding should have good conditions", and "parents should be able to keep their kids in deportation holding". But such moderate reforms won't satisfy most people who talk about concentration camps; many people (including multiple in this very comments section) mean that it's simply intolerable for illegal immigration detention centers to exist.
However, the deportation process must be humane. You can detain people who are to be deported in conditions that respect their human rights. You can allow parents of small children with US citizenship to take their children with them (assuming both parents are deported), or to make other arrangements.
The two alternatives are not (1) open borders or (2) concentration camps for illegal immigrants.