I'm already pretty firmly on the record that the continued expansion of the settlements poses a massive threat to the viability of the two-state solution of the Israeli/Palestinian conflict. The longer the settlements stay up, many argue, the more entrenched they will become -- eventually, they will be so dug in that evacuating them will become impossible, and suddenly there is no two-state solution. At that point, the only alternatives will be ethnic cleansing, outright apartheid, or a binational, one-state solution.
This is bad enough for me, because the former two options are morally intolerable and the last I consider to be pretty awful as well. But I was doing some thinking, and it occurred to me that the settlements are near-equally threatening to a one-state solution as they are to a two. There are a few Palestinian advocates who are publicly nonchalant about the settlements precisely because they signify that "the egg is already scrambled" -- that is, Israel is inexorably on the path to one-state. But the reasons that the settlements would need to be evacuated won't go away in a one-state climate. It's not as if it will suddenly be okay for Jews to be living in Ariel or Hebron just because the territories have unified.
The problem is that (a) much of the settlement territory was appropriated by outright theft of Palestinian land (as in, land to which property-owners hold real, legally enforceable deeds to) and (b) much of the settlement territory occupies the most choice, strategically important land in the West Bank (particularly with regards to water rights). In a one-state environment, there will be as much pressure from the Palestinians to remove the settlements as there were before. If the settlements aren't removed, the new government will have no legitimacy from a Palestinian perspective, and the armed factions will be extremely unlikely to accede to it.
However, all the factors that made getting rid of the settlements too perilous to make the two-state solution viable, will multiply ten-fold in a one-state environment. A large scale evacuation requires a strong state to be managed smoothly; a new binational state will undoubtedly be fragile. Settlers sometimes resist Israeli evacuation efforts; they'll be far more likely to resort to outright violence and guerrilla warfare if they perceive the evacuators as non-Jewish entirely. Commentators wonder if a full-scale Israeli evacuation of West Bank settlements would trigger a civil war; I guarantee you that such an effort by a binational government will yield one.
This, if anything, makes the settlement expansion an even scarier prospect. It's not just poison to a two-state solution, it's poison to a solution period. It is setting the stage for a conflict more violent, more intractable, and more dangerous to Jewish and Palestinian lives than anything Israel has experienced thus far. That is something I could do without.