I see virtually no commentary about the Gelb/Biden plan for Iraq, but there should be more. The current situation provides a controlled experiment of their plan, without getting much commentary on its value.
Before the Bush/Cheney ill-considered invasion of Iraq, Leslie Gelb, later joined by Joe Biden, proposed that Iraq should be divided into three relatively autonomous regions. Specifically, that would be: Kurdistan, the Sunni areas, focused on Anbar province, and the Shiite areas, dominating the remainder of the country. Their proposal was rejected, with a lot of foreign policy "experts" pointing out that it was not feasible.
Now, ten years after the US's invasion, the situation clearly shows that Gelb and Biden were correct, in my opinion. The Kurdish portion of Iraq has set itself up as a fairly autonomous region, and is prospering (at least by comparison to their neighborhood). The main problem on their horizon is refugees (and possibly worse), as the Kurdish areas in Turkey, Syria and Iran may also become restive and seek refuge in the northern Iraqi semi-state of Kurdistan. (Worse would be if those countries became concerned, and decided to invade to protect their territory.)
However, the rest of Iraq has devolved into civil war. The Shia-Sunni split in arab lands has come to a boil in this "liberated" country, and they are busy killing each other, making it a major civil war.
It is certainly possible that, had the country been tripartite divided as Gelb and Biden proposed, the violence would be far less than it currently is. I believe it is probable.
And yet, at least in the media I read, there is almost no talk of this.