Concur, but the consequences of losing Iraq are far more dire than the domino theory of Vietnam.
U.S. forces would be more effective as a force-in-being in Kurdistan, Kuwait and elsewhere than tied down trying to maintain their Main Supply Routes to Baghdad International Airport and to Kuwait.
If pulling U.S. combat units out of Baghdad and the Sunni Triangle is in the U.S. intereest, we should do it. If not, we should stay. That's the litmus test.
We lost the Vietnam War but won the Cold War when Ronald Reagan developed a strategy for winning it. He didn't invade Eastern Europe and the Soviet Uninon: He exploited the failure of Communism to bring about its demise. Today, Vietnam is America's fastest-growing export market excluding China.
There is a useful lesson in Iraq.