for 4 campaigns (5-6 scenarios) and some extra civs (3-4), I would be willing to pay up to 40 EUR. I got this game at a discounted prices (15 EUR) and I am nowhere bored with it after 100+ hours. Playing through hard and some multiplayer matches in between. The most fun I had since Bloodborne.
I would hope for campaigns of Charlemagne, War of the Roses, Louis I of Hungary, Ivan III Russia, Casimir III of Poland, the Ottoman conquest of Eastern Europe, etc. would be brilliant or perhaps something in the Americas before the Conquista or Africa during the age of exploration. I would not mind a campaign set during the dark age and feudal age entirely (the history of one of the barbaric tribes that did no make it like Avars, last scenario could be a desparate struggle to hold of castle age units for some time with some tragic end). I also loved the scenarios were certain resources were scarce or not usable (stone, wood, food) giving the game a very different dynamic.
Really one of the greatest games of all time (easy to pick up and so deep) - so for extra content I would be happy to pay.
Let’s hope for some more content, though I think I will be still busy getting all gold trophies and achievenements some months.