Yep, the situation gonna be remained complicated.
In a post-US Middle East, Iran (even with the current regime) will ally with Russia, and probably mend the relationship with Europe as the US global influence has become much weaker than now.
China and Iran only have the common interests to kick the US out of the Middle East, but most Chinese like me have always a feeling that most Iranians (the pro-west and anti-west ones) don't like China.
The capital inflow from the gulf region into China's high tech and military industrial complex sectors have expediting China's absolute dominance over the US, which gonna also insecure its own future security from the west.
Also, the western countries are fully turning into right-wing, and even without a superpower US, they might seek future alliance with Russia as the common white Christian brotherhood.
They are anti-zionism, and might seek Iran to become one of them by using the Aryan brotherhood, since most Iranians will fall for it.
Yes, indeed. I think that we will likely see a Venezuela like US/Israel installed coup in Iran. US/Israel will accept the new Iranian leadership under certain conditions and with an Iran largely aligned with the US/West again. In return they will get sanctions relief and US/Western firms will "invest" (buy up) many Iranian assets. This way most Iranians will be happy with the new Iranian regime = most ordinary people do not care about geopolitics they just want stability - economic in particular and safety. They will get that in such an arrangement.
US involvement in the region started due to the discovery of oil and gas. Ironically the British found oil first in Iran. Later locals and the West started searching in next door Iraq and Arabia.
Anyway Iran has a far more bloody/unfortunate history with the West than people in Arabia who were never impacted this negatively:
They lost half of their population in 1917 due to British/Western actions.
en.wikipedia.org
Once again during the Soviet and British occupation of Iran:
en.wikipedia.org
Then you had them installing the Pahlavi regime/dynasty in 1925.
Then the removal of Mossadegh in 1953.
en.wikipedia.org
So they have reason to dislike the West.
Compare this with KSA. Not really much to compare with.
Also have in mind that US presence (military) in the region started due to our own Arab foolishness.
Saddam invaded Kuwait and wanted to invade rest of Eastern Arabia to size all the oil and gas. This would never have been allowed by the US/World so they took him out and probably manipulated him into invading Kuwait, thinking that he would not be harmed and that the US would not care about internal Arab affairs.
This cemented their presence. 10 years later 9/11 occurred and then you had the US invasions of Iraq and Afghanistan.
Later came the Arab spring (started in Tunisia) which spread mostly to Egypt, Yemen, Sudan and Syria. Afterwards you had the rise of Daesh.
In the meantime you had events in Palestine, Hezbollah and Israeli shenanigans.
KSA/GCC had to navigate in this mess being right in the middle of this mess and one of the few safe heavens in the region. All with rapidly growing young populations and oil/economic reforms.
Look at KSA. Within 10 years completely transformed on every sphere - mostly for the better. Was unthinkable until recently.
Now you have this mess with Iran.
Lastly many of the small GCC states invited the US and others into their countries in order to protect themselves from KSA because they feared/fear KSA annexing them. Don't forget that most of those small GCC states were historically always a part of ancient civilizations, cultures, caliphates, empires, kingdoms, sultanates, emirates, imamates, sheikdoms ruled by people from modern-day KSA or based in modern-day KSA. Most of the ruling dynasties of those small GCC states are originally from KSA. Goes for Bahrain, Kuwait, Qatar, many of the 7 UAE emirates. The only exception is the ruling Ibadi Omani royal dynasty which claims Yemeni origin.
Yep, Arabs think how to subvert the west, while most Iranians want to be integrated into the west.
However, as I mentioned that the west europe is turning into far right-wing when they are turning into batsh1t crazy by seeing the permanent change of the demography in europe.
The superpower USA means the strong bastion to protect the white people, if the US is no longer existing, they might put all their bet on Russia as the new bastion for the white people, and just see what Tucker Carlson has said.
Those non-Zionist MAGA believes that the Zionists are their internal parasites/enemies for ruining the great western/white civilization, but the biggest external enemy will forever be China.
And they cannot tolerate China to become stronger than any white superpower in the history.
But as the US has been sabotaged by the Zionism, they are poised to lose the competition against China.
A western alliance with Russia to replace the US gonna become so much weaker against China.
The US was great because of so many great Chinese scientists working for them (e.g. Boeing's first leading engineer was Chinese, and many Chinese scientists have involved in the Manhattan project), but white men will always avoid to give the Chinese too much credit.
With Russia on the lead, most US elite Chinese scientists/engineers will return to serve for China, not for the Europe and Russia.
Since the Sino-USSR split, Russia is not really a genuine ally of China and vice versa. Russia at its core is an European country. 90% of the population is that. Their language, religion, culture, outlook on life etc. The only difference is that they are a transcontinental country with their own unique history that separates them from Europe. However Russian elites, Putin included, views himself as a European. The entire ruling oligarchy, many of them Jewish ironically, are also firmly aligned with the West. Look at where they have stored almost all of their wealth, investments etc.
I think that it will just be a question of time (Putin will not rule forever and you cannot escape history and geography and your own origin) before Russia returns to the West/Europe. The only reason why they were divided where ideological (political) due to the Russian revolution in 1917. From 1991 until early 2000's Russia even wanted to join NATO. The US was not interested in that as were many Eastern European nations who lobbied against it due to historical fears of Russia. Putin did not take this rejection lightly (famous Munich speech in 2008) and rest (mostly Ukraine - Crimea since 2014) is history.
As for China, if I was a Chinese, I would continue the inward looking policy and focus on reaching parity with the US. Also personally I would work towards some kind of East Asian unity with Koreans and Japanese and somehow try to tempt them away from the US sphere/orbit but I know that there is some terrible historical distrust that makes the Arab-Iranian conflict a joke largely. I am here specifically talking about the many horrific war crimes that the Japanese did against China and the Chinese people.
However at one point in time you need to move on and form some kind of East Asian bloc. You are similar people in most ways as you already know. Same can be said about us Middle Easterners/West Asians regardless of ethnicity.