"If we fail in Iraq, the terrorists win and we all lose."
A bit over the top, don't you think?
I believe that we call Iraq a draw, let the Sunnis have the civil war they obviously want, and figure out what our next move should be in the larger WOT.
Iraq is a small piece of the big picture.
"Winning" Iraq doesn't mean overall victory in the WOT, and "losing/quitting" Iraq doesn't mean overall loss in the WOT.
Iraq is more like round 2 of a 15 round heavyweight fight, IMO.
A civil war would be a failure and a victory for the insurgents.