Hello everyone, I didn't log in in a long while, but I have been lurking all these months, and I think I finally cracked the mistery of this leak. By the mistery I mean the civ selection, which doesn't feature any NA Native American, nor any SE Asian, nor the Incas and will only have at most one out of the trio Mongolia - Ottomans - Persia. All that while picking civs like Brazil or Poland which would be overall better suited for expansions.
I might be wrong, of course, but I think the key to that is the increased difference in each civ's art assets for Civ6! For those who didn't notice, Civ5 had every civ using most of the assets, so a French pikeman looked the same as a Songhai one, down to the skin colour. The only differences (besides the UUs) were the cities and the settlers. Those two elements had 5 variations, which corresponded more or less to: 1- Natives from all over America + post-colonial Latin America; 2- Europe + Anglo-Saxon America; 3- Rome, Greece and some other Mediterranean civs/CSs; 4- Middle East + Africa; 5- The whole rest of Asia. We had nations as different from each other as India, Mongolia, Samarkand, Indonesia, all having cities that looked like a Japanese city. And when the Iroquois would want to found a city, their settlers would carry their stuff in a llama. What this meant, however, was that every civ was just as easy to add. When they added the Shoshone, they only had to work on the leader and the UUs. If they wanted, they could have added the Nasca or the Tlingit or even Argentina, instead, and it would take the same amount of work.
Now, for Civ6, things are different. We've seen a much greater level of visual differentiation between civs. City models are apparently unique to each civ, and even regular fighting units have models that go along with cultural groups (China and Japan have the same model, Egypt has another). So, whenever they add a civ, they'll have different challenges according to the civ's culture. To add Poland, they would need only to take the Russian or German city models, do some small changes, and make new skins. The same for Brazil, they would take the Spanish models and tweak them. And the regular units wouldn't even need new models. Now for something like the Inca or a SE Asian civ, they would have to do a complete research on architecture, clothing, weaponry, then model the cities and units out of scratch! For a nomadic and unique culture like Mongolia, it would be even harder! I think they are saving to tackle those hurdles in future expansions, instead, while the vanilla is relatively more homogeneous, culturally. What do you guys think about that?