How many times do foreigners need to understand that Iran can never "control" a single Arab country let alone any Arabs as Arabs are a too proud and nationalistic people and moreover very few of us have a positive view of Iranians overall which is even the case in places like Iraq, Syria and Lebanon.
One of the biggest insults that you can possibly make towards an Iraqi Shia Arab is to call him an Iranian. That should tell you something.
The exception here is Hezbollah but that is a proxy so understandable but once the Mullah regime in Iran ends, which eventually will happen, Hezbollah will not die (they will lose their most important backer) but local Shia South Lebanese will still support their fight against Israel (their main enemy). So even they and their movement will live on. I am not going to include the militias aligned to Tehran that are part of the PMU (in my eyes those groups are terrorist groups and moreover traitors but as long as they can be used to fight Daesh purely and not stir up any trouble - they can be tolerated for now) are totally outnumbered by nationalists among PMU that answer to Baghdad. Therefore I do not worry about them other than local infiltration in police force etc. as we have heard/seen evidence of in Diyala, unfortunately.
Even if we assume that there were such plans by all 3 governments to change the demographics of Northern and Eastern Syria and Western and Northern Iraq, this will simply fail.
Instead of writing nonsense understand that the Iraqi Arabs in and around Kirkuk and Northern Iraq in general are almost all exclusively Sunni Arabs. Moreover almost every single one of them (if not all) support the recent push in Kirkuk. Why? Because the Kurdish terrorists and land grabbers have stolen their land. Not the land of the Iraqi Shia Arab Basrawi or Najafi. Not only that this community is the most nationalistic community in Iraq which has something to do with the history of Iraq and who ruled/dominated the country since the foundation until 2003. This includes the military.
You are giving too much power to what is an essentially impoverished and sanctioned entity that is very much divided internally on numerous fronts. At the sight of a sign of war or when such a war starts, you will see that from up close. Fire crackers won't be helpful here. US/West scaremongering is a deliberate tactic. They used it against a crippled and sanctioned Iraq before 2003 as well. It's the same story.
Anyway there is no point discussing this here with foreigners. You were probably also "believing" that Daesh would conquer Baghdad back in 2014 or that they would establish a real country as locals were in love with them, LOL.
