From where I sit, I can't see how it will end up being anything but a miserable, bloody debacle that will spill over into other countries in the region. There may not be African/Eastern European-style genocide attempts, but I still wouldn't want to be an average everything Iraqi moderate hoping to mind their own business and be left alone for the next ten years.
You could have said the same thing about Afghanistan. I would expect that the overall situation in Iraq will be about the same. Neighbouring countries are deterred enough not to get any more involved than financing terrorist strikes of various descriptions that couldn't easily be traced back to those same countries. The terrorist strikes will be mainly to cause disruption and fear. The overall death rates on such a campaign are limited, and even in say Israel, deaths from car accidents are at the same degree of magnitude. It's not pleasant, but it's endurable (Israeli's aren't showing up as refugees in general). Neither the Kurds nor the Shiite's are calling for a breakup of the country. Unlike Dr. Clam I think the only acceptable result will be a "multicultural" Iraq with borders as they are. It doesn't seem the new Iraqi police/army is strong enough to contain the organised Sunni military remnant units yet, but it looks like the US army will stay until it is.