I would be careful to count all those permutations as "civs." It will feel that way at the beginning of each age, when you only have traditions to slot. This is likely where your previous civ choice has the most impact and a Normans with Roman traditions will be quite different from a Normans with Aksum traditions. Of course, you might want to keep traditions slotted more often than not, we need to play to see how that works. But at some point, when you just slot 1 tradition, you won't feel much difference between Roman-Norman-Americans and Aksum-Norman-Americans. It's not zero, but it's probably not a full civ difference. But I think the different leaders and attribute points further diversify the game very much. Hence, I think it's also wrong to think of the modern age as "just 10 civs" because obviously, with several traditions available, a leader ability, and 10 attribute points spend, every civ can go in many different directions.