Iraq now wants foreign troops to leave the country... They find they have had enough war in their land; Go make your war somewhere else...
A logical action in the light of what just happened and before... However this is not in the interest of the USA...
Although I would like us to leave and would be happy to incur the results, the USA leaving Iraq would be a disaster for the Middle East. As Les pointed out, it would not be the end of war, but the beginning of a new one.
First, lets ask the obvious, why was an Iranian general so easily able to move throughout Iraq supporting Iranian backed militias? Because the Shiite majority (in Iraq) largely align with the Mullahs in Iran. The Shiites welcome this because of their hatred of the Sunnis and the Kurds.
Second, why was the vote held? The Shiites looked at the bombing as an opportunity to get rid of the USA, which would allow them to rule the country with impunity. The reason we know this is because all of the Sunni and Kurd representatives did not show up for the vote out of protest. So now the prime minister (who is a Shiite) faces the very serious question of supporting the resolution and aligning with his party, or allowing the USA to stay. The former will more then likely start a civil war of Shiites vs. Sunni & Kurds, whereas the latter will not get him re-elected.
Lets assume that the PM follows through and kicks the USA out. It is only a matter of time before the Shiites start oppressing the Sunnis and Kurds, and, assuming the Sunnis and Kurds fight back, then all hell breaks loose. Iraq borders Syria, with a strong Kurdish population in the North, and Jordan, a 95% Sunni country, both of which could get drawn into the fighting if a civil war begins. Of course, if the Kurds in Syria and certainly if Jordan gets involved, so will Iran.
Then Israel will need to make a decision on whether or not to get in. It could be within Israel's best interest to ally themselves with the Sunnis since they are anti Iran (enemy of my enemy thing) and it would go a long way with their neighbor Jordan. Not to mention allowing Iraq to become a proxy state of Iran would bring Iran too close for comfort for Israel. Of course, if this happened, the USA is now back in the fight.
This is a worse case scenario, but given the 1000s of years of Shiite and Sunni conflict, it is probably more likely then not civil unrest would result in Iraq.
PS, something else to consider if the Middle East gets drawn into a war with Iran and Israel being involve, is how long would it be until Israel nukes Iran? Unlike the West, Israel really has no qualms using their nukes, and eventually nuking Iran would become an option to them. So, would the world just let the ME be, knowing there is a strong possibility of a nuclear war breaking out, or would the West intervene to prevent this? Of course intervening to prevent nuclear weapons being used would mean support Israel's side, since supporting the opposing side would increase Israel's need to use their nuclear weapons.