The bottom line is that after a serious attack on Iran, most of the US army ceases to exist as a viable fighting force. The best that can happen is some kind of semi-successful retreat - which would be a military fiasco and a political disaster, castrating forever the fond image that the US has of itself as a paragon of force projection machismo.
The worst is very much worse.
after all the Marine corps appears to already see the looming disaster and are maneuvering to find themselves somewhere else
Marines Press to Remove Their Forces From Iraq - New York Times
WASHINGTON, Oct. 10 -- The Marine Corps is pressing to remove its forces from Iraq and to send marines instead to Afghanistan, to take over the leading role in combat there, according to senior military and Pentagon officials. The idea by the Marine Corps commandant would effectively leave the Iraq war in the hands of the Army while giving the Marines a prominent new role in Afghanistan, under overall NATO command.
WASHINGTON, Oct. 10 -- The Marine Corps is pressing to remove its forces from Iraq and to send marines instead to Afghanistan, to take over the leading role in combat there, according to senior military and Pentagon officials.
The idea by the Marine Corps commandant would effectively leave the Iraq war in the hands of the Army while giving the Marines a prominent new role in Afghanistan, under overall NATO command.