Maybe they will. They've been that already though.. until Calenhad. That's practically what Teyrns and barbarian factions were before.
This is also one of the importances of the Chantry though.. it smoothes out political conflict. And some of those former warlords became Andrastian and chilled out (the Ash Warriors). It's also one of the points Josephine makes about religion (but she was talking about whole nations getting along better, when they have shared values). The reason the mideast and other places get that way is because they're struggling for a unifying belief (Shia/Sunni... with Jews and Christians adding complications to the mix).
Err... I'm probably getting carried away with the comparison 
What happen in Middle East is not really religious you know, it is more political than religion, the struggle between Shia and Sunni Islam is also political, the split was political historically. The Shia was the supporter of 4th Caliph in Islam, while Sunni accept whoever being elected as Caliph. That's was the original feud between Shia and Sunni. Then the caliphate system fall when Islam spread outside Arabia region, the non-Arabs don't want to be ruled by Arab Caliphs, so they have their own rulers. There you got Abbassid of Persians, Ottoman of Turk, AlMohad of Moors, Fatimid of Egypt and so on. That's in medieval era.
The Ottoman was the ruler of a large part of Middle East, they are considered as the "Caliph" of all Muslims, not really a Caliph in sense of ruling but as an honorable title, somekind of a patron of all Muslim kingdoms in Middle East and Asia. When Ottoman fall, there you got a problem in Middle East, because there is no longer the one who powerful enough to hold everyone, so hell break loose....it was Ottoman who keep peace in that region, the most strongest and advance in their time, when they gone, all other warlords start to show their fangs...up to today it is always like that in Middle East, it is their way, democracy will never work or just don't work in that part of the world.
So the same here, it was Tehirin bloodline who hold Ferelden, when Cailan fall with no heir, no one powerful enough to hold everyone. Cousland also gone. So really, Ferelden will become like Middle East. You must remember that every Banns or Arls or nobles or whatever, have ther own army...if ever they are going into democracy, it will not going to be overnight. Loghain manage to hold everyone for a time being just because of his own position and fame, but as we can see even that is not a guarantee for him. Civil war happen during Blight, imagine that...