But, as to what would happen, if by some miracle all US troops were home tomorrow? Here’s my two bits worth, with the caveat I’m only very, very smart, not omniscient.
Civil war. Brief, loud, and conclusive. The Sunni have no chance, none, of prevailing over the Shia. At best, they might be able to sustain a fight long enough to gain some minor negotiating advantage. Most of the Muslim world has come to grips successfully with the Shia/Sunni breach, as has the Xtian world come to accept the Protestant Reformation. I expect the larger Muslim world will move to act, probably by way of the UN, to establish a peacekeeping force. Possible extra upside: the discrediting and destruction of the extremist Wahhabbi-type Sunni extremists. Like ObL, just for instance.
The Kurds will establish Kurdistan, this is almost a given at this point. The Shia will get the oil-rich south and the marshlands. The Sunni will get whats left, which is pretty much diddly squat. And so it goes. The Turks wont like it, and the Sunni wont like it, but can probably do very little about it.
Displacement as ghastly as the India-Pakistan partition is possible, but I am hopeful it won’t be as extreme. Note the operative word: “Hopeful”. Sunni who cannot live under Shia domination will be displaced, as will their counterpart Shia. But here’s the kicker: tolerant and secular Islamists will have an advantage, being able to adapt and communicate. Precisely the people we most need to foster and nurture. Secularism becomes a Social Darwinist advantage.
The oil? Will be sold, whoever sells it. There is no point in keeping it.
The cost? More than we would wish, less than we dread. But the kicker? It will almost certainly happen regardless of how long we subject our best and brightest to this pointless misery.
With reluctance and grave apprehension, nonetheless: Out Now!