100 turns into a Beta campaign, AI is forming very big empires, and is actually aggressive.

These are the largest empires I've played with since Warhammer 2. This campaign I purposely pursued peace with the Empire and Dwarfs, vassalizing a few elector counts and Ungrim. I had good relations with the Empire until the Nemisis Crown and Sword of Khaine matured, which tanked my relations with everyone. So my neighbours are at peace and nobody else attacked me beyond the Empire except the High Elves who haven't sent anyone to me and are losing hard to Morathi.

This is the priority focus CA changed I think, AI seems to deal with threats in their theatre rather than launch crusades miles away that don't help them. Miao Ying, after confederating Zhao Ming, has the whole of Cathay, Empire has complete control of Norsca, Morathi is rapidly advancing through Ulthuan and Grimgor actually survived and is expanding too. The AI doesn't leave enemies alive but works to fully control areas before moving on.

I'm actually impressed, the changes are very good. I don't know if early game was peaceful because of my diplomacy, my last vampire counts campaign I did the exact same moves (vassalize Ungrim, increase relations with the Empire, then get the SoK and NC and migrate to Nagashizzar) but the map was a lot more fragmented with the largest empires only being \~20 regions. Here you can see Clan Mors is at 22 and is the smallest empire in the top 7 (well I am) and would have been bigger if I didn't vassalize them. Good work CA finally something to test my Immortal Empires.