The assassination of general Soleimani of Iran -- not just their top military leader, but a national hero beloved by all sides of Iranian society -- heralds a realignment in Middle Eastern geopolitics.
The current era began circa 1980, coincidentally or not in tandem with the neoliberal transition in Western nations. The Islamic Revolution in Iran swept away the era of the Shah, the Saudis under the new ruling clan the Sudairi Seven switched from leading a regional movement against Israel to forming the Gulf Cooperation Council to pursue Gulf wahhabi interests, Israel left behind the Labor Zionist era and entered the Likud era, Turkey went from secular nationalist to Islamist, Egypt (and Jordan) got bought off by the Pentagon to not continue the Arab-Israeli wars, and Saddam Hussein rose to power in Iraq (de facto, then de jure) and launched the Iran-Iraq War.
Throughout the current era, Iran has been primarily defensive and reluctant to expand its sphere of influence outside its own borders. They did not try to occupy Iraq after the Iran-Iraq War, and did not even cross the border into Afghanistan when the Taliban (or their Sunni fundamentalist allies) murdered Iranian diplomats and a journalist on Afghan soil in 1998. They've mainly been concerned with withstanding the economic and military onslaught of Iraq under Hussein, Saudi Arabia, Israel, and the US.
More recently they have been key players in the Axis of Resistance, a mainly Shia group of peoples who are all the target of the superpower intervening in the region -- the US -- and its local strongmen, Saudi Arabia and Israel. The Axis is led by Iran but includes a good share of Iraq (which is majority Shia), Hezbollah and Shia fellow travelers in Lebanon and Syria, and the Houthi in Yemen. Their goal is national liberation from either the US occupation, Israeli occupation (southern Lebanon), or Saudi-sponsored Sunni extremist armies (such as al-Qaeda, ISIS, and the rest, who are aligned with the Pentagon).
This activity of Iran has taken the form of mediating among all the various parties, and not using any kind of leverage to bring the lesser partners to heel and do the bidding of Iran. Soleimani was the central figure in this role of mediation, supervision, and mentorship.
But as detailed in this post by Elijah Magnier, the Axis of Resistance was still not entirely solidified in its goals and willingness to take the fight to its enemies. This is understandable since it is not that old of an alliance.
And aside from Iran, the nations of the Axis have not been strong geopolitical powers since at least 500 BC: the Neo-Babylonian Empire was the last expansionist power from Mesopotamia, the Neo-Assyrian the last from the northern Fertile Crescent, and the Levant has never spawned a land-based expansion in Asia (although the Phoenicians did spread a sea-based empire around the Mediterranean coastline). Iran has done so several times since 500 BC, for centuries at a time, the first being the Achaemenid Empire and the most recent being the Safavid Empire that lasted into the mid-1700s.
This reliable historical pattern means that Iran will be playing the major role in the Axis -- and it also means that it will have to be more hands-on in order to make its sphere of influence most effective at deterring its encroaching enemies. If it continues to be reluctant, as during the current era, there will not be enough cohesion and the Axis will remain weak relative to its enemies.
Such a major shift in geopolitical priorities -- from staying in the background of its junior partners' politics, and moving actively into the foreground -- will require a realignment in Iranian politics. And Soleimani's martyrdom appears to be the first triggering event that will lead to such a realignment. Now they have learned that it is not enough to play a mediating role like he did -- his successors must go beyond that, to setting up a stronger Iranian presence within the Axis member nations, and using some degree of leverage to discipline them and keep them unified.
Moreover, because Soleimani was beloved as a hero by all sectors of Iranian society, his assassination will unite factions who have been in opposition to each other during the current era -- the hardliners vs. the moderates / reformists. There will still be some kind of political division in the new era, but it will be different -- some group within the hardliners will defect to the reformists, or vice vera, and create a new stable system of coalition partners, pursuing a new stable national and foreign policy.
For example, the group within the military who want to remain defensive will tend to be discredited by these events, and more influence will go to the military groups who want to outright expand Iran's presence in the region. And within the moderate reformists, influence will be taken away from those who thought they could just coax in global financial investors and not have to worry so much about regional geopolitics -- the gambit of the Iran nuclear deal. Meanwhile, influence will rise among those reformists who see a strong regional expansion -- or at least getting a nuclear weapon -- as a security precondition, to safeguard their main goal of financial / technological / cultural development within Iran proper. Once those two formerly opposing factions unite, they will pursue a common goal of regional Iranian expansion.
I'll be writing more about Iran and the region; this post is only about domestic realignment within Iran during the 2020s.