Otherwise this is lining up as a battle between Saudi-backed ISIS/ISIL Sunni militants and Shi'ite central government troops along with Iranian Al Quds forces. The proxy war is about to be much less "proxy". Looks like Baghdad will be the front from your map.

Faction left, and so now they are filling in the vacuum?

The Peshmerga are very american friendly. I remember talking to a vet who worked with them closely. He said they were very cooperative and well disciplined. They were grateful that the 2003 war stopped their persecution by Saddam. Probably the only positive thing that came out of that war.

Three main blocs:

The Sunni Arabs: That's ISIS, but it's also a lot of Sunni tribesmen and former Baathists very unhappy with Shiite control of the central government. This is more than just "Al Qaeda terrorists."

The Sunni Kurds: They have their own autonomous region and may use the collapse of the Baghdad military to grab some more territory for themselves, i.e. Kirkuk. They have share a religion with the Sunni Arabs, but not ethnicity.

The Shiite Arabs: They're the Iraqi majority and they control the south and east of the country.

has the manpower and popular support to venture further? Seems rather hopeful.

The Iranians have already pledged to protect the Shi'ite southeast of Iraq.

It was available. I posted a similar one on my now defunct blog and predicted this would happen. Along with thousands of others who saw the same thing.

What makes it even more horrifying is if you lay an oil field map on top of it. The factions will not just agree to split the country along ethnic and religious boundaries because that's not how the oil is laid out.

This is the logical consequence of "liberating" Iraq: Bloody civil war.