I don't expect the DLC pack 3 to be North America, but if it is it would be a pleasant surprise for me.I also have a sneaking suspicion that DLC pack 3 will have two North American civs. The reasoning being that (a) none of the PNW or SW tribes have strong female leaders are less likely to be pushed back to season 2 to maintain the 3-6 gender ratio, (b) none of the aforementioned tribes would likely sell well solo in DLC pack 4 or 6 compared to Portugal/Byzantium/Assyria/Italy, (c) the Inuit are an insanely popular V mod and probably the biggest dark horse candidate beyond the Goths, and (d) if we aren't getting any more African civs then there likely is no Africa map in NFP, leaving DLC pack 6 to likely be Middle Eastern/Mediterranean and begging the question why DLC pack 3 should have anything but an America map.
The most reasonable combination for that I could see is maybe the Iroquois and then another tribe out west like the Navajo/Apache or something more north like the Tlingit. The Iroquois at least have Jigonhsasee as a possible female leader.