Our ADD President doesn't understand that something as subtle as long-term strategy and goals is a thing. The same applies to his fan base.

Iran's missile attack was weak, but Iran's primary goal isn't quick revenge.

Khamenei said the U.S. should leave the region, adding, “Military action like this is not sufficient. What is important is ending the corrupting presence of America in the region,” Reuters reported.

Making America leave the region is probably out of Iran's control. However, making America leave Iraq, Afghanistan and Syria is doable.
In fact, it's quietly begun in Syria.

The United States evacuated one of its military bases in the Syrian province of Hasakeh, in the northeast corner of this country, media reported today.
...
Syrian media reported that the US military also began the evacuation of its two bases in the al-Omar oil field and the Conoco gas plant, in the northeast of the province of Deir Ezzor.

Not coincidentally, that very same oil field that Conoco just fled came under mortar attack from Iranian forces just days ago.
Interestingly, the article ended with this.

An Omani envoy who visited Iran was told that Tehran is not interested in any mediation and left without meeting with officials on Saturday, according to Al Mayadeen.

The time for talking has ended. Diplomacy between the U.S. and Iran is not possible.
The only question is the best way to get America to leave.

When it comes to getting us to leave Syria and Afghanistan, the answer is force.
They need to make us bleed, and they will.
This may go on for a long time.

Iraq, OTOH, requires a more delicate touch. Because of that, it is unlikely that Iran will launch a major offensive in Iraq.
Instead they will only do enough to make it clear to Baghdad that you must kick out the U.S. or Iran will make Iraq a warzone.

Defense Secretary Mark Esper has pointed out that Iraq’s government has made no formal request that American forces leave its country. Only making a nonbinding vote Sunday to expel U.S. troops.

Esper also criticized the nature of the Iraqi vote Sunday, which saw dozens of that country's lawmakers decline to participate in protest. Most Kurdish and Sunni members of parliament did not vote, he said. He also claimed many of the Shiite lawmakers voted to expel American troops “at threat of their own lives” from powerful Iran-backed militias in Iraq.

Even if the Iraqis do ask the United States to leave their country, Esper added, it would require "procedural mechanisms and hurdles," and it would be unlikely that American troops would leave immediately after such a request.

The first part of that statement is true.
The Kurds don't want us to leave because they never wanted to be part of Iraq in the first place.
The Sunnis trust neither Baghdad nor America.
However, Esper's last point about "procedural mechanisms and hurdles" is pure bullsh*t.

Constitutionally, draft laws that do not originate in the Iraqi cabinet are non-binding, even if they are approved by parliament.

As such, the decision to expel foreign troops from Iraq would rest with the executive, specifically the cabinet of Adel Abdul Mahdi, who has backed the parliamentary vote.

The current government is officially a caretaker government, after Abdul Mahdi announced his resignation in December following pressure from anti-government protests. This limits the actual powers the government has to enact legislation.

However, the original invitation in 2014 for coalition forces to aid Iraq in fighting the Islamic State (IS) group was not based on parliament-approved legislation, but rather on an exchange of diplomatic letters between the Iraqi foreign minister and foreign officials.

The decision to remove the forces would not require the government to draft legislation for parliament and the government could potentially withdraw the invitation unilaterally.

Sajad Jiyad, managing director of the Bayan Centre, told Middle East Eye that, therefore, if Abdul Mahdi wanted to immediately action the vote taken in parliament, he could do so.

“It would just be an exchange of notes from Iraq’s foreign ministry to the foreign ministries of other countries and it could be just a quick process,” he explained.

Just like that. It could happen tomorrow.
The vote by parliament already gave them political cover.
So what's the hold up?
A lot of internal groups are going to need to be consulted with and reassured.
That will take some time. Plus, Trump is probably applying immense pressure against it.
Expect China, Russia, and India to play some small roles.