On my second campaign currently. With configurable war attrition, I'm on day 1000 and there are 4 factions remaining.
Sturgia was the first to fall, obviously. Vlandians and Northern Empire tore them in half, I think Battania finished them off.
Southern and Western Empires fell next. The western and southern got devoured by the north empire.
Vlandia and Khuzaits split Aserai in half.
Battania was destroyed after my civil war, my faction is the 4th faction and 2nd in power. Before destroying them though, we were a powerhouse, Caladog eventually declared one too many wars and lost one too many fiefs and everyone started to hate him.
Vlandia controls 2/3 of their original territory and half of Aserai, but their days are numbered as my faction is currently throwing them out of their home territory.
The Khuzaits have dominated their home territory and are in a punching battle against the northern empire, but the northern empire has consistently pulled troops away from their eastern front to try and invade battania and vlandia which has caused them to eventually lose fiefs, and now Khuzaits are on a warpath.
My first playthrough was mostly defections to the khuzaits which led them to dominate half the map while vlandia dominated the other half. Eventually the vlandian superpower won and it was gg.