How Can Iran Be 'King of the South'?

PCG teaches that Iran will unite a large part of the Islamic world and emerge as the 'King of the South.'

This doctrine ignores the fact that Biblical geography is centered around Jerusalem, not Greenwich, and by that standard Iraq is in the East, not the South.

This doctrine also ignores the fact that Iran is Shiite, the minority strand of Islam, while most of the rest of the Islamic world is predominantly Sunni, except for southern Iraq.

Look at this, at times extremely graphic, sermon from the Saudi cleric Muhammad Al-Arifi.(Update 12.11.13: You need to register with the website to be able to see the video.)

Here he calls Sistani, the preeminent clerical leader among the Iraqi Shiites, as "a sheik who is a great sinner and infidel from a remote corner of Iraq".

He also bring up historic grievances between Sunnis and Shiites both in the distant past and today, such as the Iraq War. He gets into some pretty graphic stuff here.

Therefore how on earth are Sunni Muslims going to bow to a Shiite state when there is so much animosity between them? In the Iraq War there has been an unfathomable blood letting between the Sunni and Shia Arabs. Under Iraq, from its founding in the 1920s till 2003 it was the Sunni Arabs who lorded over the Shiites and the Kurds. Now the Shiites have gained political ascendancy and some among the Sunnis, particularly Zarqawi's Al Qaeda in Iraq, have unleashed a horrifying terrorist war to once again to bring the Shia into submission. Thankfully they seem to have lost a lot of steam due to the Anbar Awakening.

With such a frightful scar between their relations how on earth are they supposed to unite under a (presumably Shiite) Iranian King of the South when there are such terrible grievances between them?